Revert "Stop enabling g-reg by default"

This reverts commit d7dfcdb4674daae8a294848b1de6fa87c5d7d4eb. A
subsquent change that depends on this,
d8dec362baa2bf7f6ffe1c47352fdbe032eaf20a, has knock on effects for
devstack-gate and needs to be reverted. Revert this first.

Change-Id: Ic5402f57052648e10eacf3c3de67d2cdd2d42f63
Signed-off-by: Stephen Finucane <sfinucan@redhat.com>
Partial-bug: #1860021
diff --git a/stackrc b/stackrc
index 9fd7f75..2d3a599 100644
--- a/stackrc
+++ b/stackrc
@@ -69,7 +69,7 @@
     # Placement service needed for Nova
     ENABLED_SERVICES+=,placement-api,placement-client
     # Glance services needed for Nova
-    ENABLED_SERVICES+=,g-api
+    ENABLED_SERVICES+=,g-api,g-reg
     # Cinder
     ENABLED_SERVICES+=,c-sch,c-api,c-vol
     # Neutron