Fix subscription portal URLs in specs

ee/spec/features/groups/billing_spec.rb

@@ -18,7 +18,7 @@ RSpec.describe 'Groups > Billing', :js do
   end
 
   before do
-    stub_full_request("https://customers.gitlab.com/gitlab_plans?plan=#{plan}")
+    stub_full_request("#{EE::SUBSCRIPTIONS_URL}/gitlab_plans?plan=#{plan}")
       .to_return(status: 200, body: File.new(Rails.root.join('ee/spec/fixtures/gitlab_com_plans.json')))
 
     allow(Gitlab).to receive(:com?).and_return(true)

ee/spec/features/subscriptions/groups/edit_spec.rb

@@ -12,7 +12,7 @@ RSpec.describe 'Welcome screen', :js do
     before do
       group.add_owner(user)
       gitlab_sign_in(user)
-      stub_request(:get, 'https://customers.gitlab.com/gitlab_plans?plan=free')
+      stub_request(:get, "#{EE::SUBSCRIPTIONS_URL}/gitlab_plans?plan=free")
         .to_return(status: 200, body: '{}', headers: {})
 
       visit edit_subscriptions_group_path(group.path, params)

ee/spec/helpers/billing_plans_helper_spec.rb

@@ -4,7 +4,7 @@ require 'spec_helper'
 
 RSpec.describe BillingPlansHelper do
   describe '#subscription_plan_data_attributes' do
-    let(:customer_portal_url) { "https://customers.gitlab.com/subscriptions" }
+    let(:customer_portal_url) { "#{EE::SUBSCRIPTIONS_URL}/subscriptions" }
 
     let(:group) { build(:group) }
     let(:plan) do

ee/spec/services/fetch_subscription_plans_service_spec.rb

@@ -4,7 +4,7 @@ require 'spec_helper'
 
 RSpec.describe FetchSubscriptionPlansService do
   describe '#execute' do
-    let(:endpoint_url) { 'https://customers.gitlab.com/gitlab_plans' }
+    let(:endpoint_url) { "#{EE::SUBSCRIPTIONS_URL}/gitlab_plans" }
 
     subject { described_class.new(plan: 'bronze').execute }