FIX: unable to filter user directory when sorted by user field. (#15951)

Since the "users" table is already added in the "includes" method it gives unexpected results while using it again in the "joins" method.

app/controllers/directory_items_controller.rb

@@ -38,7 +38,7 @@ class DirectoryItemsController < ApplicationController
       user_field = UserField.find_by(name: params[:order])
       if user_field
         result = result
-          .joins(:user)
+          .references(:user)
           .joins("LEFT OUTER JOIN user_custom_fields ON user_custom_fields.user_id = users.id AND user_custom_fields.name = 'user_field_#{user_field.id}'")
           .order("user_custom_fields.name = 'user_field_#{user_field.id}' ASC, user_custom_fields.value #{dir}")
       end