We no longer use this cache

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/models/__init__.py

@@ -114,8 +114,6 @@ def update_comment_flag(sender, instance, **kwargs):
         # Invalidate counts cache
         if instance.language is None:
             unit.translation.invalidate_cache('sourcecomments')
-        else:
-            unit.translation.invalidate_cache('comments')
 
 
 @receiver(post_delete, sender=Suggestion)