Fix warnings while running redmine:load_default_data rake task (#33310).

Patch by Go MAEDA.


git-svn-id: http://svn.redmine.org/redmine/trunk@19715 e93f8b46-1217-0410-a6f0-8f06a7374b81

lib/tasks/load_default_data.rake

@@ -2,7 +2,6 @@ desc 'Load Redmine default configuration data. Language is chosen interactively
 
 namespace :redmine do
   task :load_default_data => :environment do
-    require 'custom_field'
     include Redmine::I18n
     set_language_if_valid('en')