Generate random keystone users

Change-Id: I8dbd07b10d29b43d1c35fa76bcaa0f0efb32beda
Related-Prod: PROD-29868
diff --git a/heat/server/cluster.yml b/heat/server/cluster.yml
index be2f211..89a5885 100644
--- a/heat/server/cluster.yml
+++ b/heat/server/cluster.yml
@@ -34,7 +34,7 @@
         host: ${_param:openstack_database_address}
         port: 3306
         name: heat
-        user: heat
+        user: ${_param:mysql_heat_username}
         password: ${_param:mysql_heat_password}
         x509:
           enabled: ${_param:openstack_mysql_x509_enabled}
@@ -60,7 +60,7 @@
         host: ${_param:cluster_vip_address}
         port: 35357
         tenant: service
-        user: heat
+        user: ${_param:keystone_heat_username}
         password: ${_param:keystone_heat_password}
         protocol: ${_param:cluster_internal_protocol}
       message_queue: