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/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