DEV: Ignore bookmarks.topic_id column and remove references to it in code (#14289)

We don't need no stinkin' denormalization! This commit ignores
the topic_id column on bookmarks, to be deleted at a later date.
We don't really need this column and it's better to rely on the
post.topic_id as the canonical topic_id for bookmarks, then we
don't need to remember to update both columns if the bookmarked
post moves to another topic.

lib/topic_view.rb

@@ -392,6 +392,7 @@ class TopicView
 
   def has_bookmarks?
     return false if @user.blank?
+    return false if @topic.trashed?
     @topic.bookmarks.exists?(user_id: @user.id)
   end