Revert "FEATURE: Publish read state on group messages. (#7989) [Undo revert] (#8024)"

This reverts commit 5dda5c2f7c.

lib/topic_view.rb

@@ -109,14 +109,6 @@ class TopicView
     @personal_message = @topic.private_message?
   end
 
-  def show_read_indicator?
-    return false unless @user || topic.private_message?
-
-    topic.allowed_groups.any? do |group|
-      group.publish_read_state? && group.users.include?(@user)
-    end
-  end
-
   def canonical_path
     path = relative_url.dup
     path <<