Generate random keystone users

Depends-On: https://gerrit.mcp.mirantis.com/#/c/44319/
Depends-On: https://gerrit.mcp.mirantis.com/#/c/45118/
Depends-On: https://gerrit.mcp.mirantis.com/#/c/45119/

Related-Prod: PROD-29868
Related-Prod: PROD-31315
(cherry picked from commit f5956c2f6151cc5d99659103f90641ea66eac44a)
(cherry picked from commit 70dd0f0587eb297fbefdea43837839c4983b8378)

Change-Id: I402be73437d5397224184a4fd71e2f6abae24db2
diff --git a/nova/control/cluster.yml b/nova/control/cluster.yml
index 437f3c1..325c6a5 100644
--- a/nova/control/cluster.yml
+++ b/nova/control/cluster.yml
@@ -43,7 +43,7 @@
         host: ${_param:openstack_database_address}
         port: 3306
         name: nova
-        user: nova
+        user: ${_param:mysql_nova_username}
         password: ${_param:mysql_nova_password}
         x509:
           enabled: ${_param:openstack_mysql_x509_enabled}
@@ -57,7 +57,7 @@
         region: ${_param:openstack_region}
         host: ${_param:cluster_vip_address}
         port: 35357
-        user: nova
+        user: ${_param:keystone_nova_username}
         password: ${_param:keystone_nova_password}
         tenant: service
         protocol: ${_param:cluster_internal_protocol}
@@ -95,7 +95,7 @@
         engine: neutron
         region: ${_param:openstack_region}
         host: ${_param:neutron_service_host}
-        user: neutron
+        user: ${_param:keystone_neutron_username}
         password: ${_param:keystone_neutron_password}
         port: 9696
         mtu: 1500