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/metadata/service/server/single.yml b/metadata/service/server/single.yml
index 950074f..d761f56 100644
--- a/metadata/service/server/single.yml
+++ b/metadata/service/server/single.yml
@@ -40,3 +40,12 @@
             enabled: ${_param:openstack_fluentd_handler_enabled}
           ossyslog:
             enabled: ${_param:openstack_ossyslog_handler_enabled}
+      cache:
+        engine: memcached
+        expiration_time: 600
+        backend_argument:
+          memcached_expire_time:
+            value: 660
+        members:
+        - host: ${_param:single_address}
+          port: 11211