Rework backup code to only back up to remotes in DEV_REMOTES
Rework backup code to only back up to remotes in DEV_REMOTES

Earlier, it was trying to always back up to all remotes, which might
not always be possible.

rsalevsky/crowbar,vwallfahrer/crowbar,rhafer/crowbar,rhafer/crowbar,MaximilianMeister/crowbar,tserong/crowbar,mmnelemane/crowbar,mmnelemane/crowbar,aplanas/crowbar,toabctl/crowbar,SUSE-Cloud/crowbar,crowbar/crowbar,nkrinner/crowbar,SUSE-Cloud/crowbar,aspiers/crowbar,rhafer/crowbar,vwallfahrer/crowbar,crowbar/crowbar,aspiers/crowbar,dirkmueller/crowbar,toabctl/crowbar,MaximilianMeister/crowbar,nkrinner/crowbar,aplanas/crowbar,dirkmueller/crowbar,tserong/crowbar,rsalevsky/crowbar