Generate random keystone users

Change-Id: I8dbd07b10d29b43d1c35fa76bcaa0f0efb32beda
Related-Prod: PROD-29868
diff --git a/manila/common/single.yml b/manila/common/single.yml
index 00f42eb..fe59263 100644
--- a/manila/common/single.yml
+++ b/manila/common/single.yml
@@ -26,7 +26,7 @@
         host: ${_param:single_address}
         port: 3306
         name: manila
-        user: manila
+        user: ${_param:mysql_manila_username}
         password: ${_param:mysql_manila_password}
         x509:
           enabled: ${_param:openstack_mysql_x509_enabled}
@@ -40,7 +40,7 @@
         region: ${_param:openstack_region}
         host: ${_param:single_address}
         port: 35357
-        user: manila
+        user: ${_param:keystone_manila_username}
         password: ${_param:keystone_manila_password}
         tenant: service
         auth_type: password