aliases/implications: remove forum topic updating code.

Remove code for updating forum topics when an alias or implication is
approved or rejected. This code was only used when approving single
alias or implication requests. This is no longer used now that all
alias/implication requests are done through BURs.

app/logical/forum_updater.rb

@@ -5,7 +5,6 @@ class ForumUpdater
     @forum_topic = forum_topic
     @forum_post = options[:forum_post]
     @expected_title = options[:expected_title]
-    @skip_update = options[:skip_update]
   end
 
   def update(message, title_tag = nil)
@@ -32,7 +31,6 @@ class ForumUpdater
   end
 
   def update_post(body)
-    return if @skip_update
     forum_post.update(body: "#{forum_post.body}\n\nEDIT: #{body}", skip_mention_notifications: true)
   end
 end