Generate random keystone users

Change-Id: I8dbd07b10d29b43d1c35fa76bcaa0f0efb32beda
Related-Prod: PROD-29868
diff --git a/galera/server/database/grafana.yml b/galera/server/database/grafana.yml
index 3bfee87..3afb436 100644
--- a/galera/server/database/grafana.yml
+++ b/galera/server/database/grafana.yml
@@ -7,12 +7,12 @@
         grafana:
           encoding: utf8
           users:
-          - name: grafana
+          - name: ${_param:mysql_grafana_username}
             password: ${_param:mysql_grafana_password}
             host: '%'
             rights: all
             ssl_option: ${_param:mysql_grafana_ssl_option}
-          - name: grafana
+          - name: ${_param:mysql_grafana_username}
             password: ${_param:mysql_grafana_password}
             host: ${_param:cluster_local_address}
             rights: all