Use cloud-images.ubuntu.com rsync module instead of uec-images
uec-images rsync module was not migrated during recent server
migration. It has since been restored but I see no reason to
depend on it's existence. We should use the known and widely
used cloud-images module instead.
Drop fast path use of keystoneauth1 sessions object.
There is no harm in passing all of the kwargs to both
glance and swift client objects and for swift, passing
just the session is not sufficient to correctly set
cacert and other security related settings.