Changing DB engine value

The patch chnages DB engine value from mysql+pymsql
to mysql in order arrange the value and to be used
in templates, other configuration snippet, etc. like
other salt-formulas have.

Change-Id: I0d843e48f57ea2c3bc76011b27ec45978f48a8d3
diff --git a/aodh/server/cluster.yml b/aodh/server/cluster.yml
index 00a8263..0a590cf 100644
--- a/aodh/server/cluster.yml
+++ b/aodh/server/cluster.yml
@@ -14,7 +14,7 @@
       verbose: true
       region: ${_param:openstack_region}
       database:
-        engine: "mysql+pymysql"
+        engine: "mysql"
         host: ${_param:openstack_database_address}
         port: 3306
         name: aodh