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/grafana/server/single.yml b/grafana/server/single.yml
index 6303430..c7aa8a9 100644
--- a/grafana/server/single.yml
+++ b/grafana/server/single.yml
@@ -15,7 +15,7 @@
         host: ${_param:openstack_database_address}
         port: 3306
         name: grafana
-        user: grafana
+        user: ${_param:mysql_grafana_username}
         password: ${_param:mysql_grafana_password}
       auth:
         basic: