Fix finding matrix room that is already joined (home-assistant#67967)

After some debugging, it seems room.canonical_alias contains the
room alias that matches the room_id_or_alias value but is not
contained in room.aliases (which is empty). As a result, the
matrix component thought the room wasn't alread joined, joins
again, and this replaces the previous room which had the listener.
This resulted in the component callback not being called for new
messages in the room.

This fixes home-assistant#66372

homeassistant/components/matrix/__init__.py

@@ -243,7 +243,10 @@ def _join_or_get_room(self, room_id_or_alias):
                 room.update_aliases()
                 self._aliases_fetched_for.add(room.room_id)
 
-            if room_id_or_alias in room.aliases:
+            if (
+                room_id_or_alias in room.aliases
+                or room_id_or_alias == room.canonical_alias
+            ):
                 _LOGGER.debug(
                     "Already in room %s (known as %s)", room.room_id, room_id_or_alias
                 )