slapos_web_deploy: try to do apt-get update also without "--allow-releaseinfo-change"

This is a fixup for 5c938a8d.
3 jobs for master in 0 seconds (queued for 1 second)
Status Job ID Name Coverage
  External
failed SlapOS-Master.UnitTest-Master

01:04:21

failed SlapOS.Eggs.UnitTest-Master.Python2

00:20:19

failed SlapOS.Eggs.UnitTest-Master.Python3

00:25:42