Remove unnecessary line that changes the @PluginLoader@ directory inside @plugins_test.rb@ (#36320).

git-svn-id: https://svn.redmine.org/redmine/trunk@22510 e93f8b46-1217-0410-a6f0-8f06a7374b81

test/unit/lib/redmine/plugin_test.rb

@@ -27,8 +27,6 @@ class Redmine::PluginTest < ActiveSupport::TestCase
     # In case some real plugins are installed
     @klass.clear
 
-    # Change plugin loader's directory for testing
-    Redmine::PluginLoader.directory = @klass.directory
     Redmine::PluginLoader.setup
   end