Add cinder service user metadata

Enable cinder service user by default

Change-Id: I7bd21385b43cefa8b8a95f9d11f0c007b6cc9f2b
Related-Prod: PROD-25985
diff --git a/cinder/volume/single.yml b/cinder/volume/single.yml
index 9531aa4..a865722 100644
--- a/cinder/volume/single.yml
+++ b/cinder/volume/single.yml
@@ -44,6 +44,8 @@
         host: ${_param:openstack_control_address}
         protocol: ${_param:cluster_internal_protocol}
         region: ${_param:openstack_region}
+      service_user:
+        enabled: ${_param:cinder_service_user_enabled}
       cache:
         security:
           enabled: ${_param:cinder_memcache_security_enabled}