Make addon systemd services depend on the homeserver systemd service as well, not just on Traefik

Addons typically access the homeserver via Traefik, but requests
ultimately lead to the homeserver and it'd better be up or Traefik would
serve a "404 Not Found" error.

This is an attempt (one of many pieces) to make services more reliable,
especially when `devture_systemd_service_manager_service_restart_mode: all-at-once` is used
(which is the default).

group_vars/matrix_servers

@@ -212,7 +212,20 @@ matrix_homeserver_app_service_config_files_auto: |
 
 matrix_addons_homeserver_container_network: "{{ matrix_playbook_reverse_proxy_container_network if matrix_playbook_internal_matrix_client_api_traefik_entrypoint_enabled else matrix_homeserver_container_network }}"
 matrix_addons_homeserver_client_api_url: "{{ ('http://' + matrix_playbook_reverse_proxy_hostname + ':' + matrix_playbook_internal_matrix_client_api_traefik_entrypoint_port | string) if matrix_playbook_internal_matrix_client_api_traefik_entrypoint_enabled else matrix_homeserver_container_url }}"
-matrix_addons_homeserver_systemd_services_list: "{{ ([traefik_identifier + '.service'] if matrix_playbook_reverse_proxy_type == 'playbook-managed-traefik' else []) if matrix_playbook_internal_matrix_client_api_traefik_entrypoint_enabled else matrix_homeserver_systemd_services_list }}"
+matrix_addons_homeserver_systemd_services_list: |
+  {{
+    (
+      matrix_homeserver_systemd_services_list
+      +
+      (
+        [traefik_identifier + '.service']
+        if matrix_playbook_reverse_proxy_type == 'playbook-managed-traefik'
+        else []
+      )
+    )
+    if matrix_playbook_internal_matrix_client_api_traefik_entrypoint_enabled
+    else matrix_homeserver_systemd_services_list
+  }}
 
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