CoreServices list has to be flatten

Just like other lists this one needs to be flatten

Closes-Bug: #1947193
Change-Id: I1e46bdf73cbd4d5e6e5eb0abd61d5e54bec63e11

common/services/role.role.j2.yaml

@@ -138,7 +138,7 @@ resources:
       value:
         map_merge:
           yaql:
-            expression: list(coalesce($.data.role_data, []).where($ != null).select($.get('core_services')).where($ != null))
+            expression: list(coalesce($.data.role_data, []).where($ != null).select($.get('core_services')).where($ != null)).flatten()
             data: {role_data: {get_attr: [ServiceChain, role_data]}}
 
   ServiceConfigSettings: