Fix neutron invalid json file

Fix a missing comma in config.json when neutron_plugin_agent is set
to 'vmware_nsxv' or 'vmware_dvs'.

Closes-Bug: #1720380

Change-Id: I088f09a426a5435202176c45a77b1fbc19468f97

ansible/roles/neutron/templates/neutron-server.json.j2

@@ -42,7 +42,7 @@
             "source": "{{ container_config_directory }}/nsx.ini",
             "dest": "/etc/neutron/plugins/vmware/nsx.ini",
             "owner": "neutron",
-            "optional": {{ (neutron_plugin_agent not in ['vmware_nsxv', 'vmware_dvs']) | string | lower }}
+            "optional": {{ (neutron_plugin_agent not in ['vmware_nsxv', 'vmware_dvs']) | string | lower }},
             "perm": "0600"
         }{% endif %}
     ],