So TripleO is moving to not building undercloud images. In doing so
they used the obvious name for a dictionary of images just like
we did. This causes issues since the config vars take precedence over
our own group_vars. Replace with more discriptive var name.
Also changed are the meadata gathering functions to use the overcloud
image instead of the now non existant undercloud one.
Finally collectd openstack has to handle the inclusion of a different
version of collectd by default now.
Change-Id: Ie29c1c2070ffe88e015a1a04bdb4834cf14f1e5c
c82559b65a