Add GTM to /users/sign_up/groups_project/new view

ee/app/views/registrations/groups_projects/new.html.haml

@@ -3,7 +3,9 @@
 - page_title _('Your GitLab group')
 - form_params = { trial_onboarding_flow: params[:trial_onboarding_flow], glm_source: params[:glm_source], glm_content: params[:glm_content], skip_trial: params[:skip_trial] }
 - content_for :page_specific_javascripts do
+  = render "layouts/google_tag_manager_head"
   = render "layouts/one_trust"
+= render "layouts/google_tag_manager_body"
 
 .row.gl-flex-grow-1
   .gl-display-flex.gl-flex-direction-column.gl-align-items-center.gl-w-full.gl-px-5.gl-pb-5

ee/spec/views/registrations/groups_projects/new.html.haml_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'registrations/groups_projects/new' do
+  let(:google_tag_manager_id) { 'GTM-WWKMTWS'}
+
+  let_it_be(:user) { create(:user) }
+  let_it_be(:group) { create(:group) }
+  let_it_be(:project) { create(:project) }
+
+  before do
+    assign(:group, group)
+    assign(:project, project)
+    stub_config(extra: { google_tag_manager_id: google_tag_manager_id, google_tag_manager_nonce_id: google_tag_manager_id })
+    allow(view).to receive(:current_user).and_return(user)
+    allow(view).to receive(:import_sources_enabled?).and_return(false)
+  end
+
+  context 'when Google Tag Manager is enabled' do
+    before do
+      allow(view).to receive(:google_tag_manager_enabled?).and_return(true)
+      render
+    end
+
+    subject { rendered }
+
+    it 'contains a Google Tag Manager tag' do
+      is_expected.to match(/www.googletagmanager.com/)
+    end
+  end
+
+  context 'when Google Tag Manager is disabled' do
+    before do
+      allow(view).to receive(:google_tag_manager_enabled?).and_return(false)
+      render
+    end
+
+    subject { rendered }
+
+    it 'does not contain a Google Tag Manager tag' do
+      is_expected.not_to match(/www.googletagmanager.com/)
+    end
+  end
+end