There are a few places where we have a play with one task that uses the
group_by module to generate groups that are used in a subsequent play.
These plays do not need to gather facts for their target hosts.

In particular, the kolla-openstack.yml playbook should really be able to
operate without access to remote hosts.

This change also adds changed_when: false to all group_by tasks, since
they show as changed but haven't really made any changes outside of
Ansible.

TrivialFix

Change-Id: I18f67eda4e48058f3f402b9d0e692d6eeb02855f