Be more aggressive in overriding the BROKER_URL

* because Invenio-App-RDM sets a default value for that config item
  mismatching our setup

invenio_config_tuw/startup/config.py

@@ -116,12 +116,11 @@ def assemble_broker_uri_from_parts(app):
     broker_user = _get_config(app, "BROKER_USER", default=rabbitmq_user)
     broker_password = _get_config(app, "BROKER_PASSWORD", default=rabbitmq_password)
 
-    if broker_url is None:
-        if None not in [broker_protocol, broker_user, broker_password, broker_host]:
-            broker_url = (
-                f"{broker_protocol}://{broker_user}:{broker_password}@{broker_host}/"
-            )
-    else:
+    if None not in [broker_protocol, broker_user, broker_password, broker_host]:
+        broker_url = (
+            f"{broker_protocol}://{broker_user}:{broker_password}@{broker_host}/"
+        )
+    elif broker_url is None:
         broker_url = "amqp://guest:guest@localhost:5672/"
 
     # celery doesn't like having BROKER_HOST *and* the other values set