Enable oslo.cache library

Add aodh:server:cache metadata

      cache:
        engine: memcached
        expiration_time: 600
        backend_argument:
          memcached_expire_time:
            value: 660
        members:
        - host: ${_param:cluster_node01_address}
          port: 11211
        - host: ${_param:cluster_node02_address}
          port: 11211
        - host: ${_param:cluster_node01_address}
          port: 11211

Enable oslo.cache in the aodh.conf file

Change-Id: I4445faafb95c3d7b4a88bd033c65cc0ba99f2488
Related-Prod: PROD-26960
diff --git a/tests/pillar/server_cluster.sls b/tests/pillar/server_cluster.sls
index e25b502..9cf1c07 100644
--- a/tests/pillar/server_cluster.sls
+++ b/tests/pillar/server_cluster.sls
@@ -47,6 +47,10 @@
       store_events: default
     cache:
       engine: memcached
+      expiration_time: 600
+      backend_argument:
+        memcached_expire_time:
+          value: 660
       members:
       - host: 127.0.0.1
         port: 11211