Change module BillingPlansHelper to prependable

ee/app/helpers/billing_plans_helper.rb

@@ -187,3 +187,5 @@ module BillingPlansHelper
     end
   end
 end
+
+BillingPlansHelper.prepend_mod

ee/spec/helpers/billing_plans_helper_spec.rb

@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe BillingPlansHelper do
+RSpec.describe BillingPlansHelper, skip: Gitlab.jh? do
   include Devise::Test::ControllerHelpers
 
   describe '#subscription_plan_data_attributes' do