Fix oslo_db host in Barbican Helm overrides (#351)

Author: sowm9802

helm-configs.example/barbican/barbican-helm-overrides.yaml

@@ -604,7 +604,7 @@ endpoints:
         username: barbican
         password: password
     hosts:
-      default: mariadb-galera-primary
+      default: mariadb-cluster-primary
     host_fqdn_override:
       default: null
     path: /barbican