Add service defined ansible_group_vars to RoleGroupVars

This would allow us not to merge them manually when doing
config-download.

Change-Id: Ic0af64bfd2f16e6a54d09e525499276d9c330a27

overcloud.j2.yaml

@@ -1302,6 +1302,7 @@ outputs:
 {%- for role in roles %}
       {{role.name}}:
         map_merge:
+        - {get_attr: [{{role.name}}ServiceChainRoleData, value, ansible_group_vars]}
         - {get_attr: [{{role.name}}GroupVars, value]}
         - {get_attr: [{{role.name}}ConfigData, value]}
         - any_errors_fatal: {get_param: {{role.name}}AnyErrorsFatal}