Fix bridges failing to upload media when Synapse workers are enabled

roles/matrix-base/defaults/main.yml

@@ -72,6 +72,11 @@ matrix_ntpd_service: "{{ 'ntpd' if ansible_os_family == 'RedHat' or ansible_dist
 
 matrix_homeserver_url: "https://{{ matrix_server_fqn_matrix }}"
 
+# Specifies where the homeserver is on the container network.
+# Where this is depends on whether there's a reverse-proxy in front of it, etc.
+# This likely gets overriden elsewhere.
+matrix_homeserver_container_url: "http://matrix-synapse:8008"
+
 matrix_identity_server_url: ~
 
 matrix_integration_manager_rest_url: ~