Remove `rkt` from container runtime options
Remove `rkt` from container runtime options

Part of efforts to clean up mentions of rkt in kubelet.

rkt was removed entirely in 1.11, in favor of using `rktlet` and CRI
instead. It should no longer be listed at all as a runtime.

warmchang/kubernetes,coolsvap/kubernetes,stevesloka/kubernetes,dixudx/kubernetes,sanjeevm0/kubernetes,iameli/kubernetes,huangjiuyuan/kubernetes,davidz627/kubernetes,liggitt/kubernetes,xlgao-zju/kubernetes,idvoretskyi/kubernetes,tallclair/kubernetes,enj/kubernetes,fejta/kubernetes,tpepper/kubernetes,xlgao-zju/kubernetes,iameli/kubernetes,tallclair/kubernetes,enj/kubernetes,andrewrynhard/kubernetes,liggitt/kubernetes,jackfrancis/kubernetes,kpgriffith/kubernetes,cmluciano/kubernetes,maciaszczykm/kubernetes,chrislovecnm/kubernetes,ixdy/kubernetes,jackfrancis/kubernetes,zetaab/kubernetes,u2takey/kubernetes,feiskyer/kubernetes,gnufied/kubernetes,deads2k/kubernetes,kitt1987/kubernetes,tallclair/kubernetes,andrewrynhard/kubernetes,liggitt/kubernetes,soltysh/kubernetes,iameli/kubernetes,micahhausler/kubernetes,mosoft521/kubernetes,mengqiy/kubernetes,kitt1987/kubernetes,carlory/kubernetes,csrwng/kubernetes,rnaveiras/kubernetes,weiwei04/kubernetes,pwittrock/kubernetes,joelsmith/kubernetes,PI-Victor/kubernetes,ingvagabund/kubernetes,bparees/kubernetes,derekwaynecarr/kubernetes,weiwei04/kubernetes,fejta/kubernetes,k82cn/kubernetes,yujuhong/kubernetes,jingxu97/kubernetes,brendandburns/kubernetes,idvoretskyi/kubernetes,MHBauer/kubernetes,stevesloka/kubernetes,sethpollack/kubernetes,cofyc/kubernetes,JacobTanenbaum/kubernetes,maciaszczykm/kubernetes,sdminonne/kubernetes,iterion/kubernetes,weiwei04/kubernetes,fgimenez/kubernetes,MHBauer/kubernetes,mkumatag/kubernetes,MikeSpreitzer/kubernetes,kevin-wangzefeng/kubernetes,verb/kubernetes,fanzhangio/kubernetes,zhouhaibing089/kubernetes,tomzhang/kubernetes,klaus1982/kubernetes,jfrazelle/kubernetes,stevesloka/kubernetes,tomzhang/kubernetes,dlorenc/kubernetes,andrewrynhard/kubernetes,stevesloka/kubernetes,mikedanese/kubernetes,rafax/kubernetes,dlorenc/kubernetes,coolsvap/kubernetes,jingxu97/kubernetes,joelsmith/kubernetes,GulajavaMinistudio/kubernetes,rnaveiras/kubernetes,hex108/kubernetes,LalatenduMohanty/kubernetes,shyamjvs/kubernetes,dereknex/kubernetes,kevensen/kubernetes,maciaszczykm/kubernetes,pmorie/kubernetes,kubernetes/kubernetes,joelsmith/kubernetes,warmchang/kubernetes,frodenas/kubernetes,iterion/kubernetes,x13n/kubernetes,zhangmingld/kubernetes,mYmNeo/kubernetes,luxas/kubernetes,sethpollack/kubernetes,xychu/kubernetes,spzala/kubernetes,aveshagarwal/kubernetes,idvoretskyi/kubernetes,MHBauer/kubernetes,x13n/kubernetes,cblecker/kubernetes,BenTheElder/kubernetes,chestack/kubernetes,dereknex/kubernetes,idvoretskyi/kubernetes,Lion-Wei/kubernetes,sethpollack/kubernetes,jdef/kubernetes,kevin-wangzefeng/kubernetes,tcnghia/kubernetes,krmayankk/kubernetes,pweil-/kubernetes,wongma7/kubernetes,fanzhangio/kubernetes,k82/kubernetes,fejta/kubernetes,huangjiuyuan/kubernetes,gnufied/kubernetes,rrati/kubernetes,ii/kubernetes,gnufied/kubernetes,chrislovecnm/kubernetes,openshift/kubernetes,pweil-/kubernetes,k82/kubernetes,openshift/kubernetes,pwittrock/kubernetes,alejandroEsc/kubernetes,PiotrProkop/kubernetes,verult/kubernetes,carlory/kubernetes,k82cn/kubernetes,tomzhang/kubernetes,matthyx/kubernetes,luxas/kubernetes,Lion-Wei/kubernetes,andrewrynhard/kubernetes,mboersma/kubernetes,cmluciano/kubernetes,iterion/kubernetes,mYmNeo/kubernetes,tomzhang/kubernetes,monopole/kubernetes,lojies/kubernetes,kevin-wangzefeng/kubernetes,ingvagabund/kubernetes,jdef/kubernetes,weiwei04/kubernetes,andrewrynhard/kubernetes,mkumatag/kubernetes,openshift/kubernetes,tallclair/kubernetes,gnufied/kubernetes,verult/kubernetes,saad-ali/kubernetes,sanjeevm0/kubernetes,maciaszczykm/kubernetes,tomzhang/kubernetes,PI-Victor/kubernetes,jsafrane/kubernetes,pwittrock/kubernetes,soltysh/kubernetes,mosoft521/kubernetes,linux-on-ibm-z/kubernetes,rnaveiras/kubernetes,bparees/kubernetes,ixdy/kubernetes,du2016/kubernetes,jdef/kubernetes,pmorie/kubernetes,xlgao-zju/kubernetes,mahak/kubernetes,mosoft521/kubernetes,kpgriffith/kubernetes,tomerf/kubernetes,ii/kubernetes,joelsmith/kubernetes,cmluciano/kubernetes,wanghaoran1988/kubernetes,ravisantoshgudimetla/kubernetes,fgimenez/kubernetes,openshift/kubernetes,nckturner/kubernetes,krmayankk/kubernetes,jfrazelle/kubernetes,kubernetes/kubernetes,andrewrynhard/kubernetes,wongma7/kubernetes,mahak/kubernetes,klaus1982/kubernetes,wanghaoran1988/kubernetes,MikeSpreitzer/kubernetes,dims/kubernetes,GulajavaMinistudio/kubernetes,matthyx/kubernetes,JacobTanenbaum/kubernetes,sethpollack/kubernetes,monopole/kubernetes,iameli/kubernetes,jagosan/kubernetes,zhouhaibing089/kubernetes,spzala/kubernetes,xychu/kubernetes,tomzhang/kubernetes,iterion/kubernetes,dlorenc/kubernetes,hex108/kubernetes,mkumatag/kubernetes,kitt1987/kubernetes,cblecker/kubernetes,pweil-/kubernetes,nak3/kubernetes,derekwaynecarr/kubernetes,LalatenduMohanty/kubernetes,fejta/kubernetes,nak3/kubernetes,kubernetes/kubernetes,pweil-/kubernetes,micahhausler/kubernetes,humblec/kubernetes,kpgriffith/kubernetes,ixdy/kubernetes,xlgao-zju/kubernetes,wongma7/kubernetes,monopole/kubernetes,kubernetes/kubernetes,mboersma/kubernetes,PiotrProkop/kubernetes,ravisantoshgudimetla/kubernetes,csrwng/kubernetes,fabriziopandini/kubernetes,mikebrow/kubernetes,k82/kubernetes,sdminonne/kubernetes,Acidburn0zzz/kubernetes,linux-on-ibm-z/kubernetes,du2016/kubernetes,x13n/kubernetes,ping035627/kubernetes,spzala/kubernetes,ravilr/kubernetes,kubernetes/kubernetes,feiskyer/kubernetes,zhangmingld/kubernetes,andrewsykim/kubernetes,hex108/kubernetes,mboersma/kubernetes,mYmNeo/kubernetes,rafax/kubernetes,tomerf/kubernetes,chrislovecnm/kubernetes,aledbf/kubernetes,olivierlemasle/kubernetes,li-ang/kubernetes,monopole/kubernetes,derekwaynecarr/kubernetes,x13n/kubernetes,frodenas/kubernetes,enj/kubernetes,feiskyer/kubernetes,cmluciano/kubernetes,x13n/kubernetes,xychu/kubernetes,k82cn/kubernetes,xlgao-zju/kubernetes,mYmNeo/kubernetes,alejandroEsc/kubernetes,pires/kubernetes,mengqiy/kubernetes,pires/kubernetes,nckturner/kubernetes,mikebrow/kubernetes,chrislovecnm/kubernetes,wongma7/kubernetes,ii/kubernetes,tengqm/kubernetes,yujuhong/kubernetes,tomzhang/kubernetes,kevensen/kubernetes,maciaszczykm/kubernetes,k82cn/kubernetes,nikhita/kubernetes,shyamjvs/kubernetes,fabriziopandini/kubernetes,stevesloka/kubernetes,jsafrane/kubernetes,jagosan/kubernetes,feiskyer/kubernetes,huangjiuyuan/kubernetes,kpgriffith/kubernetes,ravisantoshgudimetla/kubernetes,u2takey/kubernetes,mosoft521/kubernetes,jessfraz/kubernetes,luxas/kubernetes,aledbf/kubernetes,mikedanese/kubernetes,mfojtik/kubernetes,johscheuer/kubernetes,roberthbailey/kubernetes,krmayankk/kubernetes,openshift/kubernetes,ixdy/kubernetes,rrati/kubernetes,MHBauer/kubernetes,saad-ali/kubernetes,MikeSpreitzer/kubernetes,tcnghia/kubernetes,yarntime/kubernetes,ingvagabund/kubernetes,MHBauer/kubernetes,Lion-Wei/kubernetes,verult/kubernetes,liggitt/kubernetes,dims/kubernetes,alejandroEsc/kubernetes,olivierlemasle/kubernetes,frodenas/kubernetes,johscheuer/kubernetes,matthyx/kubernetes,jingxu97/kubernetes,cblecker/kubernetes,warmchang/kubernetes,iameli/kubernetes,Clarifai/kubernetes,zetaab/kubernetes,spzala/kubernetes,ravilr/kubernetes,maciaszczykm/kubernetes,Lion-Wei/kubernetes,frodenas/kubernetes,li-ang/kubernetes,nikhita/kubernetes,sdminonne/kubernetes,jackfrancis/kubernetes,huangjiuyuan/kubernetes,yarntime/kubernetes,mahak/kubernetes,zhouhaibing089/kubernetes,fanzhangio/kubernetes,deads2k/kubernetes,tpepper/kubernetes,rafax/kubernetes,enj/kubernetes,k82/kubernetes,mahak/kubernetes,li-ang/kubernetes,du2016/kubernetes,zhangmingld/kubernetes,rafax/kubernetes,mikebrow/kubernetes,ingvagabund/kubernetes,yujuhong/kubernetes,saad-ali/kubernetes,erwinvaneyk/kubernetes,pires/kubernetes,fabriziopandini/kubernetes,joelsmith/kubernetes,erwinvaneyk/kubernetes,pmorie/kubernetes,xlgao-zju/kubernetes,JacobTanenbaum/kubernetes,ping035627/kubernetes,mboersma/kubernetes,mahak/kubernetes,stevesloka/kubernetes,nckturner/kubernetes,jdef/kubernetes,jessfraz/kubernetes,wanghaoran1988/kubernetes,Clarifai/kubernetes,feiskyer/kubernetes,davidz627/kubernetes,jsafrane/kubernetes,davidz627/kubernetes,csrwng/kubernetes,cofyc/kubernetes,yujuhong/kubernetes,cofyc/kubernetes,coolsvap/kubernetes,yarntime/kubernetes,tomerf/kubernetes,roberthbailey/kubernetes,dlorenc/kubernetes,soltysh/kubernetes,klaus1982/kubernetes,mfojtik/kubernetes,johscheuer/kubernetes,derekwaynecarr/kubernetes,Acidburn0zzz/kubernetes,micahhausler/kubernetes,lojies/kubernetes,pmorie/kubernetes,verult/kubernetes,andrewsykim/kubernetes,kevensen/kubernetes,matthyx/kubernetes,tpepper/kubernetes,jingxu97/kubernetes,ingvagabund/kubernetes,humblec/kubernetes,pwittrock/kubernetes,brendandburns/kubernetes,enj/kubernetes,nak3/kubernetes,sanjeevm0/kubernetes,tpepper/kubernetes,nckturner/kubernetes,roberthbailey/kubernetes,erwinvaneyk/kubernetes,ravilr/kubernetes,huangjiuyuan/kubernetes,nckturner/kubernetes,monopole/kubernetes,li-ang/kubernetes,mboersma/kubernetes,jessfraz/kubernetes,mkumatag/kubernetes,olivierlemasle/kubernetes,frodenas/kubernetes,pweil-/kubernetes,johscheuer/kubernetes,BenTheElder/kubernetes,Acidburn0zzz/kubernetes,matthyx/kubernetes,tengqm/kubernetes,fgimenez/kubernetes,nikhita/kubernetes,dixudx/kubernetes,GulajavaMinistudio/kubernetes,thockin/kubernetes,tallclair/kubernetes,dims/kubernetes,thockin/kubernetes,shyamjvs/kubernetes,wanghaoran1988/kubernetes,ii/kubernetes,tcnghia/kubernetes,tengqm/kubernetes,chrislovecnm/kubernetes,tomzhang/kubernetes,pwittrock/kubernetes,Lion-Wei/kubernetes,aveshagarwal/kubernetes,jfrazelle/kubernetes,kevensen/kubernetes,wanghaoran1988/kubernetes,mYmNeo/kubernetes,liggitt/kubernetes,brendandburns/kubernetes,verult/kubernetes,rrati/kubernetes,mboersma/kubernetes,xychu/kubernetes,aledbf/kubernetes,andrewsykim/kubernetes,mfojtik/kubernetes,zhouhaibing089/kubernetes,mYmNeo/kubernetes,pires/kubernetes,Acidburn0zzz/kubernetes,pmorie/kubernetes,kitt1987/kubernetes,carlory/kubernetes,brendandburns/kubernetes,thockin/kubernetes,carlory/kubernetes,Clarifai/kubernetes,fanzhangio/kubernetes,yarntime/kubernetes,huangjiuyuan/kubernetes,dims/kubernetes,bparees/kubernetes,saad-ali/kubernetes,linux-on-ibm-z/kubernetes,erwinvaneyk/kubernetes,dereknex/kubernetes,joelsmith/kubernetes,LalatenduMohanty/kubernetes,dixudx/kubernetes,nak3/kubernetes,verult/kubernetes,mikedanese/kubernetes,humblec/kubernetes,Clarifai/kubernetes,mengqiy/kubernetes,erwinvaneyk/kubernetes,linux-on-ibm-z/kubernetes,bparees/kubernetes,gnufied/kubernetes,mfojtik/kubernetes,linux-on-ibm-z/kubernetes,nak3/kubernetes,jessfraz/kubernetes,cmluciano/kubernetes,fgimenez/kubernetes,PI-Victor/kubernetes,soltysh/kubernetes,brendandburns/kubernetes,LalatenduMohanty/kubernetes,chestack/kubernetes,PiotrProkop/kubernetes,kitt1987/kubernetes,ravisantoshgudimetla/kubernetes,cblecker/kubernetes,ravilr/kubernetes,fgimenez/kubernetes,aledbf/kubernetes,pires/kubernetes,MikeSpreitzer/kubernetes,verb/kubernetes,mosoft521/kubernetes,humblec/kubernetes,tomzhang/kubernetes,soltysh/kubernetes,weiwei04/kubernetes,ravisantoshgudimetla/kubernetes,aveshagarwal/kubernetes,krmayankk/kubernetes,dlorenc/kubernetes,cblecker/kubernetes,hex108/kubernetes,kevin-wangzefeng/kubernetes,csrwng/kubernetes,cofyc/kubernetes,csrwng/kubernetes,mikedanese/kubernetes,u2takey/kubernetes,tpepper/kubernetes,tcnghia/kubernetes,derekwaynecarr/kubernetes,erwinvaneyk/kubernetes,fanzhangio/kubernetes,ixdy/kubernetes,frodenas/kubernetes,PiotrProkop/kubernetes,alejandroEsc/kubernetes,MikeSpreitzer/kubernetes,k82cn/kubernetes,ii/kubernetes,yujuhong/kubernetes,idvoretskyi/kubernetes,tengqm/kubernetes,olivierlemasle/kubernetes,Acidburn0zzz/kubernetes,GulajavaMinistudio/kubernetes,hex108/kubernetes,johscheuer/kubernetes,kevin-wangzefeng/kubernetes,dereknex/kubernetes,ixdy/kubernetes,dereknex/kubernetes,BenTheElder/kubernetes,spzala/kubernetes,jfrazelle/kubernetes,andrewsykim/kubernetes,xychu/kubernetes,zhangmingld/kubernetes,deads2k/kubernetes,du2016/kubernetes,cmluciano/kubernetes,mfojtik/kubernetes,krmayankk/kubernetes,fabriziopandini/kubernetes,dixudx/kubernetes,davidz627/kubernetes,chestack/kubernetes,olivierlemasle/kubernetes,LalatenduMohanty/kubernetes,pires/kubernetes,mikebrow/kubernetes,zhangmingld/kubernetes,chestack/kubernetes,fejta/kubernetes,jdef/kubernetes,tcnghia/kubernetes,alejandroEsc/kubernetes,micahhausler/kubernetes,tengqm/kubernetes,BenTheElder/kubernetes,johscheuer/kubernetes,coolsvap/kubernetes,jagosan/kubernetes,tomerf/kubernetes,pweil-/kubernetes,yarntime/kubernetes,cofyc/kubernetes,mboersma/kubernetes,wongma7/kubernetes,klaus1982/kubernetes,jessfraz/kubernetes,aveshagarwal/kubernetes,jsafrane/kubernetes,zhangmingld/kubernetes,dims/kubernetes,lojies/kubernetes,sanjeevm0/kubernetes,ping035627/kubernetes,humblec/kubernetes,aveshagarwal/kubernetes,kitt1987/kubernetes,davidz627/kubernetes,luxas/kubernetes,luxas/kubernetes,sanjeevm0/kubernetes,Clarifai/kubernetes,mboersma/kubernetes,brendandburns/kubernetes,mengqiy/kubernetes,davidz627/kubernetes,zetaab/kubernetes,kevensen/kubernetes,micahhausler/kubernetes,shyamjvs/kubernetes,ping035627/kubernetes,JacobTanenbaum/kubernetes,chestack/kubernetes,JacobTanenbaum/kubernetes,iterion/kubernetes,MHBauer/kubernetes,rnaveiras/kubernetes,dixudx/kubernetes,GulajavaMinistudio/kubernetes,deads2k/kubernetes,rnaveiras/kubernetes,iterion/kubernetes,x13n/kubernetes,verb/kubernetes,fabriziopandini/kubernetes,nikhita/kubernetes,thockin/kubernetes,zetaab/kubernetes,PI-Victor/kubernetes,coolsvap/kubernetes,mengqiy/kubernetes,saad-ali/kubernetes,zetaab/kubernetes,tcnghia/kubernetes,ingvagabund/kubernetes,sdminonne/kubernetes,BenTheElder/kubernetes,ravilr/kubernetes,Lion-Wei/kubernetes,hex108/kubernetes,roberthbailey/kubernetes,verb/kubernetes,idvoretskyi/kubernetes,kpgriffith/kubernetes,carlory/kubernetes,kpgriffith/kubernetes,zetaab/kubernetes,jackfrancis/kubernetes,xychu/kubernetes,pwittrock/kubernetes,wanghaoran1988/kubernetes,fgimenez/kubernetes,saad-ali/kubernetes,rrati/kubernetes,andrewsykim/kubernetes,li-ang/kubernetes,warmchang/kubernetes,nikhita/kubernetes,mikebrow/kubernetes,Clarifai/kubernetes,bparees/kubernetes,mfojtik/kubernetes,u2takey/kubernetes,yarntime/kubernetes,cofyc/kubernetes,thockin/kubernetes,nak3/kubernetes,coolsvap/kubernetes,PI-Victor/kubernetes,aveshagarwal/kubernetes,PI-Victor/kubernetes,krmayankk/kubernetes,mikedanese/kubernetes,andrewsykim/kubernetes,JacobTanenbaum/kubernetes,jfrazelle/kubernetes,fanzhangio/kubernetes,derekwaynecarr/kubernetes,jsafrane/kubernetes,weiwei04/kubernetes,jackfrancis/kubernetes,dlorenc/kubernetes,du2016/kubernetes,ping035627/kubernetes,verb/kubernetes,roberthbailey/kubernetes,shyamjvs/kubernetes,lojies/kubernetes,chrislovecnm/kubernetes,Acidburn0zzz/kubernetes,k82/kubernetes,aledbf/kubernetes,zhouhaibing089/kubernetes,PiotrProkop/kubernetes,dereknex/kubernetes,fejta/kubernetes,jagosan/kubernetes,rrati/kubernetes,ravisantoshgudimetla/kubernetes,pmorie/kubernetes,tomerf/kubernetes,mkumatag/kubernetes,jagosan/kubernetes,luxas/kubernetes,sethpollack/kubernetes,sanjeevm0/kubernetes,jdef/kubernetes,jingxu97/kubernetes,LalatenduMohanty/kubernetes,lojies/kubernetes,tallclair/kubernetes,deads2k/kubernetes,tpepper/kubernetes,u2takey/kubernetes,warmchang/kubernetes,u2takey/kubernetes,yujuhong/kubernetes,sdminonne/kubernetes,tomerf/kubernetes