Generate random keystone users

Change-Id: I8dbd07b10d29b43d1c35fa76bcaa0f0efb32beda
Related-Prod: PROD-29868
diff --git a/galera/server/database/panko.yml b/galera/server/database/panko.yml
index c4c455a..3e00e5a 100644
--- a/galera/server/database/panko.yml
+++ b/galera/server/database/panko.yml
@@ -7,12 +7,12 @@
         panko:
           encoding: utf8
           users:
-          - name: panko
+          - name: ${_param:mysql_panko_username}
             password: ${_param:mysql_panko_password}
             host: '%'
             rights: all
             ssl_option: ${_param:mysql_panko_ssl_option}
-          - name: panko
+          - name: ${_param:mysql_panko_username}
             password: ${_param:mysql_panko_password}
             host: ${_param:cluster_local_address}
             rights: all