Turn statsd back on, but not for api main app, only for delivery

workers.

manifest.yml.j2

@@ -3,6 +3,9 @@
     'NOTIFY_APP_NAME': 'api',
     'disk_quota': '2G',
     'sqlalchemy_pool_size': 30,
+    'additional_env_vars': {
+      'STATSD_HOST': None
+    },
     'routes': {
       'preview': ['api.notify.works'],
       'staging': ['api.staging-notify.works'],