Fix interface address for memcached atop kubernetes

Change-Id: I0fdbef7c5a2bfc13e01c26d8107c7ad03881b520
Partially-implements: blueprint api-interface-bind-address-override
Depends-On: Ia0e4951c327be01b717aebb86ef4c3a4e7ed170e

ansible/roles/memcached/templates/memcached.json.j2

 {
-    "command": "/usr/bin/memcached -vv -l {{ hostvars[inventory_hostname]['ansible_' + api_interface]['ipv4']['address'] }} -p {{ memcached_port }}",
+    "command": "/usr/bin/memcached -vv -l {{ api_interface_address }} -p {{ memcached_port }}",
     "config_files": []
 }