Fix mongodb cluster using wrong network interface

MongoDB cluster only uses api_interface.

Change-Id: If24a1c9bd685b268068cb676a28316636af52b78
Closes-Bug: #1626339

ansible/roles/mongodb/templates/bootstrap_cluster.js.j2

@@ -6,7 +6,7 @@ printjson(rs.initiate(
       {% for host in groups["mongodb"] %}
       {
         "_id" : {{ loop.index }},
-        "host" : "{{ hostvars[host]['ansible_' + hostvars[host]['storage_interface']]['ipv4']['address'] }}:{{ mongodb_port }}"
+        "host" : "{{ hostvars[host]['ansible_' + hostvars[host]['api_interface']]['ipv4']['address'] }}:{{ mongodb_port }}"
       }{% if not loop.last %},{% endif %}
       {% endfor %}
     ]