Reduce service user permissions

Most of the services create the service user with the admin permission.
This is unnecessary for token validation and they should be restricted
to only having the service role.

Change-Id: Id7a9366d2c6a36139240f64371002362dc2d8d3b
diff --git a/lib/ceilometer b/lib/ceilometer
index f03bab2..8fff910 100644
--- a/lib/ceilometer
+++ b/lib/ceilometer
@@ -108,7 +108,7 @@
     # Ceilometer
     if [[ "$ENABLED_SERVICES" =~ "ceilometer-api" ]]; then
 
-        create_service_user "ceilometer" "admin"
+        create_service_user "ceilometer"
 
         if [[ "$KEYSTONE_CATALOG_BACKEND" = 'sql' ]]; then
             local ceilometer_service=$(get_or_create_service "ceilometer" \