40: Update references of GNOME OS ostree repo to the new URL
Infrastructure team is migrating GNOME Nightly and GNOME OS ostree repositories to AWS EC2 instance due to performance issues of production Ceph cluster used for the boring data. We also use this opportunity to give flat-manager instance used for GNOME OS a proper domain.
Backport !1483 (merged)
Edited by Javier Jardón