Stop enabling g-reg by default

Per [1] Glance registry should not be required to run since Queens.

[1] https://specs.openstack.org/openstack/glance-specs/specs/queens/approved/glance/deprecate-registry.html

Change-Id: I93325cbd26dbc6a30062d9ba83acab248897b18e
Depends-on: https://review.opendev.org/702707
Related-bug: #1859847
2 files changed