A spec to Deprecate the Glance Registry Service[0] was accepted in Newton,
but it contained the ambiguous statement, "Mark the service as deprecated
and ready for removal in the Q release." kolla-ansible disable the
glance-registry in Q release[1], and since we are in S now,
remove glance-registry is safe.

[0]: http://specs.openstack.org/openstack/glance-specs/specs/newton/approved/glance/deprecate-registry.html
[1]: https://review.openstack.org/#/c/566804/

Change-Id: I48f794029e97aa6f76bbd500e33f28f51a3f2ac4