raft: fix TestNodeStepUnblock
raft: fix TestNodeStepUnblock

The test cases have side-effect. We need to stop testing if one of the test
fails. Also timeout should be much longer to avoid false-positive.

OyTao/etcd_learning,joshix/etcd,qqsun8819/etcd,jlamillan/etcd,luxas/etcd,westhood/etcd,OyTao/etcd_learning,sebrandon1/etcd,rnaveiras/etcd,purpleidea/etcd,ktateish/etcd,xiang90/etcd,mqliang/etcd,dannysauer/etcd,coreos/etcd,jonboulle/etcd,swingbach/etcd,li-ang/etcd,linuxcer/etcd,whuwxl/etcd,chipironcin/etcd,mqliang/etcd,yudai/etcd,wantonsolutions/dinv-etcd,armstrongli/etcd,mickep76/etcd,xiang90/etcd,glycerine/etcd,rnaveiras/etcd,insequent/etcd,lorneli/etcd,zaphod-concur/etcd,fanminshi/etcd,nekto0n/etcd,bdarnell/etcd,ajityagaty/etcd,fanminshi/etcd,glevand/coreos--etcd,joshix/etcd,akauppi/etcd,YuleiXiao/etcd,chipironcin/etcd,endocode/etcd,zaphod-concur/etcd,armstrongli/etcd,swingbach/etcd,handsomesun/etcd,visheshnp/etcd,jlamillan/etcd,qqsun8819/etcd,glycerine/etcd,visheshnp/etcd,coreos/etcd,a-robinson/etcd,endocode/etcd,mqliang/etcd,jonboulle/etcd,hongchaodeng/etcd,mickep76/etcd,sofuture/etcd,linuxcer/etcd,heyitsanthony/etcd,insequent/etcd,luxas/etcd,etcd-io/etcd,sinsharat/etcd,gyuho/etcd,ajityagaty/etcd,CrazyJvm/etcd,gyuho/etcd,lorneli/etcd,cockroachdb/etcd,wantonsolutions/dinv-etcd,StorReduce/etcd,rnaveiras/etcd,rchicoli/etcd,mkumatag/etcd,mkumatag/etcd,yudai/etcd,ravigadde/etcd,li-ang/etcd,nekto0n/etcd,ajityagaty/etcd,cockroachdb/etcd,dannysauer/etcd,sebrandon1/etcd,StorReduce/etcd,ravigadde/etcd,bdarnell/etcd,ktateish/etcd,lumjjb/etcd,etcd-io/etcd,akauppi/etcd,plasticbox/etcd,tguangch/etcd,wantonsolutions/dinv-etcd,sofuture/etcd,tguangch/etcd,lumjjb/etcd,plasticbox/etcd,mkumatag/etcd,vimalk78/etcd,hongchaodeng/etcd,vimalk78/etcd,whuwxl/etcd,bluebreezecf/etcd,etcd-io/etcd,sinsharat/etcd,westhood/etcd,rchicoli/etcd,YuleiXiao/etcd,a-robinson/etcd,handsomesun/etcd,heyitsanthony/etcd,CrazyJvm/etcd,bluebreezecf/etcd,glevand/coreos--etcd,purpleidea/etcd