Add Gnocchi cache configuration

Change-Id: Ib4691dfe76bc024632913dd3c2109dda486d307c
(cherry picked from commit 019a7047820975a91777b1b25a171cd3295e00fb)
diff --git a/classes/cluster/virtual-mcp11-aio-telemetry/openstack/init.yml b/classes/cluster/virtual-mcp11-aio-telemetry/openstack/init.yml
index 100606d..08852f7 100755
--- a/classes/cluster/virtual-mcp11-aio-telemetry/openstack/init.yml
+++ b/classes/cluster/virtual-mcp11-aio-telemetry/openstack/init.yml
@@ -55,6 +55,12 @@
       database:
         ssl:
           enabled: ${_param:galera_ssl_enabled}
+    server:
+      cache:
+        engine: memcached
+        members:
+        - host: ${_param:single_address}
+          port: 11211
   aodh:
     server:
       database: