Fix the group check for glance-registry

TrivialFix

Change-Id: I5f279008aae6f7630abaa30b6b3d725ff5003764

ansible/roles/glance/tasks/precheck.yml

@@ -21,5 +21,5 @@
     connect_timeout: 1
     state: stopped
   when:
-    - inventory_hostname in groups[glance_services['glance-api']['group']]
+    - inventory_hostname in groups[glance_services['glance-registry']['group']]
     - container_facts['glance_registry'] is not defined