Revert "SECURITY: Don't allow moderators to view the admins inbox"

Superseeded by d9a5280f5665d12bf46efd8cdcc6200da2cdedd8

This reverts commit 18d35bf64a.

lib/topic_query.rb

@@ -540,8 +540,7 @@ class TopicQuery
               SELECT group_id
               FROM group_users
               WHERE user_id = #{user.id.to_i}
-              OR #{user.admin?}
-              OR (#{user.staff?} AND group_id <> #{Group::AUTO_GROUPS[:admins]})
+              OR #{user.staff?}
             )
           )
           AND group_id IN (SELECT id FROM groups WHERE name ilike ?)