Enable oslo.cache library

    Add gnocchi:server:cache metadata:

          cache:
            engine: memcached
            expiration_time: 600
            backend_argument:
              memcached_expire_time:
                value: 660
            members:
            - host:
              port: 11211
            - host:
              port: 11211
            - host:
              port: 11211

    Enable oslo.cache in the gnocchi.conf file

    Related-Prod: PROD-26960

Change-Id: I1ccde3bd2e0ba907188ac40cb9e5dd45e606ec5b
diff --git a/tests/pillar/server_cluster.sls b/tests/pillar/server_cluster.sls
index b9f1415..ba5ee05 100644
--- a/tests/pillar/server_cluster.sls
+++ b/tests/pillar/server_cluster.sls
@@ -51,6 +51,10 @@
       auth_type: password
     cache:
       engine: memcached
+      expiration_time: 600
+      backend_argument:
+        memcached_expire_time:
+          value: 660
       members:
       - host: 127.0.1.1
         port: 11211