Remove default_stream addition and deletion from update_stream_backend.
Remove default_stream addition and deletion from update_stream_backend.

Default stream addition/removal is done via the /default_stream REST
endpoints.

ahmadassaf/zulip,sup95/zulip,peguin40/zulip,vabs22/zulip,AZtheAsian/zulip,reyha/zulip,jrowan/zulip,TigorC/zulip,JPJPJPOPOP/zulip,zulip/zulip,rht/zulip,jrowan/zulip,susansls/zulip,j831/zulip,calvinleenyc/zulip,rishig/zulip,dattatreya303/zulip,brainwane/zulip,vaidap/zulip,Jianchun1/zulip,souravbadami/zulip,rht/zulip,AZtheAsian/zulip,sup95/zulip,cosmicAsymmetry/zulip,mahim97/zulip,Juanvulcano/zulip,mahim97/zulip,peguin40/zulip,zacps/zulip,PhilSk/zulip,souravbadami/zulip,kou/zulip,joyhchen/zulip,ahmadassaf/zulip,kou/zulip,PhilSk/zulip,jphilipsen05/zulip,jainayush975/zulip,dattatreya303/zulip,shubhamdhama/zulip,calvinleenyc/zulip,showell/zulip,rishig/zulip,PhilSk/zulip,timabbott/zulip,reyha/zulip,synicalsyntax/zulip,Galexrt/zulip,TigorC/zulip,brainwane/zulip,grave-w-grave/zulip,vaidap/zulip,jackrzhang/zulip,sonali0901/zulip,j831/zulip,isht3/zulip,dawran6/zulip,TigorC/zulip,kou/zulip,Diptanshu8/zulip,zulip/zulip,reyha/zulip,samatdav/zulip,kou/zulip,timabbott/zulip,krtkmj/zulip,KingxBanana/zulip,amyliu345/zulip,zacps/zulip,zulip/zulip,shubhamdhama/zulip,jackrzhang/zulip,eeshangarg/zulip,Diptanshu8/zulip,showell/zulip,Diptanshu8/zulip,grave-w-grave/zulip,sharmaeklavya2/zulip,shubhamdhama/zulip,hackerkid/zulip,eeshangarg/zulip,hackerkid/zulip,j831/zulip,samatdav/zulip,Jianchun1/zulip,zulip/zulip,shubhamdhama/zulip,samatdav/zulip,ahmadassaf/zulip,synicalsyntax/zulip,christi3k/zulip,amyliu345/zulip,jrowan/zulip,blaze225/zulip,aakash-cr7/zulip,amanharitsh123/zulip,arpith/zulip,AZtheAsian/zulip,peguin40/zulip,kou/zulip,dawran6/zulip,brockwhittaker/zulip,verma-varsha/zulip,sup95/zulip,isht3/zulip,krtkmj/zulip,rht/zulip,aakash-cr7/zulip,andersk/zulip,vikas-parashar/zulip,AZtheAsian/zulip,ahmadassaf/zulip,jackrzhang/zulip,Jianchun1/zulip,mohsenSy/zulip,sharmaeklavya2/zulip,eeshangarg/zulip,shubhamdhama/zulip,sonali0901/zulip,peguin40/zulip,jainayush975/zulip,timabbott/zulip,synicalsyntax/zulip,souravbadami/zulip,Galexrt/zulip,arpith/zulip,Juanvulcano/zulip,vikas-parashar/zulip,verma-varsha/zulip,mohsenSy/zulip,sonali0901/zulip,SmartPeople/zulip,timabbott/zulip,arpith/zulip,arpith/zulip,paxapy/zulip,joyhchen/zulip,PhilSk/zulip,christi3k/zulip,arpith/zulip,krtkmj/zulip,andersk/zulip,showell/zulip,krtkmj/zulip,jainayush975/zulip,ryanbackman/zulip,hackerkid/zulip,rht/zulip,joyhchen/zulip,hackerkid/zulip,grave-w-grave/zulip,ryanbackman/zulip,vaidap/zulip,dawran6/zulip,rht/zulip,TigorC/zulip,vaidap/zulip,brainwane/zulip,jackrzhang/zulip,krtkmj/zulip,verma-varsha/zulip,kou/zulip,dhcrzf/zulip,isht3/zulip,peguin40/zulip,blaze225/zulip,joyhchen/zulip,vaidap/zulip,jphilipsen05/zulip,JPJPJPOPOP/zulip,Juanvulcano/zulip,christi3k/zulip,j831/zulip,vikas-parashar/zulip,timabbott/zulip,jainayush975/zulip,dattatreya303/zulip,sup95/zulip,verma-varsha/zulip,peguin40/zulip,sharmaeklavya2/zulip,souravbadami/zulip,jainayush975/zulip,amyliu345/zulip,grave-w-grave/zulip,krtkmj/zulip,ryanbackman/zulip,punchagan/zulip,cosmicAsymmetry/zulip,vabs22/zulip,grave-w-grave/zulip,rishig/zulip,brainwane/zulip,mahim97/zulip,niftynei/zulip,dhcrzf/zulip,TigorC/zulip,Jianchun1/zulip,mahim97/zulip,Diptanshu8/zulip,niftynei/zulip,eeshangarg/zulip,Diptanshu8/zulip,KingxBanana/zulip,brockwhittaker/zulip,umkay/zulip,ryanbackman/zulip,susansls/zulip,umkay/zulip,rht/zulip,tommyip/zulip,umkay/zulip,brockwhittaker/zulip,mohsenSy/zulip,sonali0901/zulip,andersk/zulip,eeshangarg/zulip,amanharitsh123/zulip,ahmadassaf/zulip,blaze225/zulip,tommyip/zulip,amanharitsh123/zulip,brockwhittaker/zulip,reyha/zulip,calvinleenyc/zulip,KingxBanana/zulip,punchagan/zulip,Galexrt/zulip,jackrzhang/zulip,samatdav/zulip,aakash-cr7/zulip,JPJPJPOPOP/zulip,blaze225/zulip,brainwane/zulip,joyhchen/zulip,umkay/zulip,PhilSk/zulip,mohsenSy/zulip,dawran6/zulip,showell/zulip,JPJPJPOPOP/zulip,reyha/zulip,mahim97/zulip,Juanvulcano/zulip,rht/zulip,tommyip/zulip,susansls/zulip,amyliu345/zulip,souravbadami/zulip,Juanvulcano/zulip,rishig/zulip,dattatreya303/zulip,vikas-parashar/zulip,samatdav/zulip,paxapy/zulip,Diptanshu8/zulip,andersk/zulip,jrowan/zulip,timabbott/zulip,umkay/zulip,vaidap/zulip,niftynei/zulip,krtkmj/zulip,hackerkid/zulip,AZtheAsian/zulip,mahim97/zulip,jackrzhang/zulip,sup95/zulip,amanharitsh123/zulip,vabs22/zulip,rishig/zulip,sharmaeklavya2/zulip,timabbott/zulip,PhilSk/zulip,reyha/zulip,jphilipsen05/zulip,mohsenSy/zulip,blaze225/zulip,grave-w-grave/zulip,SmartPeople/zulip,tommyip/zulip,jphilipsen05/zulip,brockwhittaker/zulip,zacps/zulip,shubhamdhama/zulip,AZtheAsian/zulip,jrowan/zulip,rishig/zulip,hackerkid/zulip,ahmadassaf/zulip,souravbadami/zulip,cosmicAsymmetry/zulip,ryanbackman/zulip,amanharitsh123/zulip,jphilipsen05/zulip,niftynei/zulip,calvinleenyc/zulip,calvinleenyc/zulip,tommyip/zulip,sonali0901/zulip,vabs22/zulip,zacps/zulip,jrowan/zulip,christi3k/zulip,susansls/zulip,amyliu345/zulip,vabs22/zulip,isht3/zulip,KingxBanana/zulip,KingxBanana/zulip,samatdav/zulip,SmartPeople/zulip,paxapy/zulip,dhcrzf/zulip,brainwane/zulip,calvinleenyc/zulip,brainwane/zulip,verma-varsha/zulip,Galexrt/zulip,Jianchun1/zulip,zacps/zulip,andersk/zulip,jainayush975/zulip,sonali0901/zulip,jackrzhang/zulip,TigorC/zulip,isht3/zulip,dawran6/zulip,punchagan/zulip,Jianchun1/zulip,synicalsyntax/zulip,zulip/zulip,joyhchen/zulip,isht3/zulip,paxapy/zulip,amyliu345/zulip,SmartPeople/zulip,Galexrt/zulip,dhcrzf/zulip,Galexrt/zulip,susansls/zulip,punchagan/zulip,zulip/zulip,punchagan/zulip,aakash-cr7/zulip,sharmaeklavya2/zulip,punchagan/zulip,tommyip/zulip,andersk/zulip,showell/zulip,niftynei/zulip,kou/zulip,vikas-parashar/zulip,showell/zulip,niftynei/zulip,paxapy/zulip,christi3k/zulip,shubhamdhama/zulip,umkay/zulip,blaze225/zulip,dhcrzf/zulip,zulip/zulip,aakash-cr7/zulip,cosmicAsymmetry/zulip,verma-varsha/zulip,sharmaeklavya2/zulip,arpith/zulip,umkay/zulip,andersk/zulip,eeshangarg/zulip,JPJPJPOPOP/zulip,paxapy/zulip,zacps/zulip,rishig/zulip,dattatreya303/zulip,amanharitsh123/zulip,tommyip/zulip,mohsenSy/zulip,Galexrt/zulip,vabs22/zulip,SmartPeople/zulip,hackerkid/zulip,KingxBanana/zulip,synicalsyntax/zulip,dattatreya303/zulip,showell/zulip,synicalsyntax/zulip,cosmicAsymmetry/zulip,dawran6/zulip,j831/zulip,j831/zulip,jphilipsen05/zulip,susansls/zulip,ryanbackman/zulip,cosmicAsymmetry/zulip,Juanvulcano/zulip,dhcrzf/zulip,SmartPeople/zulip,synicalsyntax/zulip,dhcrzf/zulip,JPJPJPOPOP/zulip,aakash-cr7/zulip,eeshangarg/zulip,vikas-parashar/zulip,punchagan/zulip,sup95/zulip,ahmadassaf/zulip,christi3k/zulip,brockwhittaker/zulip