Generate random keystone users

Change-Id: I8dbd07b10d29b43d1c35fa76bcaa0f0efb32beda
Related-Prod: PROD-29868
diff --git a/keystone/server/cluster.yml b/keystone/server/cluster.yml
index 824c6b5..fe75629 100644
--- a/keystone/server/cluster.yml
+++ b/keystone/server/cluster.yml
@@ -46,7 +46,7 @@
         host: ${_param:openstack_database_address}
         name: keystone
         password: ${_param:mysql_keystone_password}
-        user: keystone
+        user: ${_param:mysql_keystone_username}
         x509:
           enabled: ${_param:openstack_mysql_x509_enabled}
           ca_file: ${_param:mysql_keystone_ssl_ca_file}