Enable oslo.cache library

    Add panko: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 panko.conf file

    Related-Prod: PROD-26960

Change-Id: I713806fd1a6687c739d098a71ada4a550ff914f3
diff --git a/tests/pillar/server_cluster.sls b/tests/pillar/server_cluster.sls
index de177d1..521a30b 100644
--- a/tests/pillar/server_cluster.sls
+++ b/tests/pillar/server_cluster.sls
@@ -24,6 +24,10 @@
       password: misterio
     cache:
       engine: memcached
+      expiration_time: 600
+      backend_argument:
+        memcached_expire_time:
+          value: 660
       members:
         - host: 127.0.0.1
           port: 11211