Fix worker listening addresses

Not specifying bind addresses for the worker resulted in this warning:

> synapse.app - 47 - WARNING - None - Failed to listen on 0.0.0.0, continuing because listening on [::]

Additionally, metrics listening only on 127.0.0.1 seems like a no-op.
Only having it accessible from within the container is likely not what
we intend. Changed that to all interfaces as well.

Whether it actually gets exposed or not depends on the systemd service
and `matrix_synapse_workers_container_host_bind_address`.

roles/matrix-synapse/templates/synapse/worker.yaml.j2

@@ -8,6 +8,7 @@ worker_replication_http_port: {{ matrix_synapse_replication_http_port }}
 worker_listeners:
 {% if matrix_synapse_worker_details.type not in [ 'appservice', 'federation_sender', 'pusher' ] %}
   - type: http
+    bind_addresses: ['::']
     port: {{ matrix_synapse_worker_details.port }}
     resources:
       - names:
@@ -22,7 +23,7 @@ worker_listeners:
 {% endif %}
 {% if matrix_synapse_metrics_enabled %}
   - type: metrics
-    bind_address: ['127.0.0.1']
+    bind_addresses: ['::']
     port: {{ matrix_synapse_worker_details.metrics_port }}
 {% endif %}