Move pendo implementation to ee only

- should not be part of FOSS as per our guidelines

app/views/admin/application_settings/integrations.html.haml

@@ -29,4 +29,4 @@
     = render 'third_party_offers', application_setting: @application_setting
 
 = render 'admin/application_settings/snowplow', expanded: expanded_by_default?
-= render 'admin/application_settings/pendo'
+= render_if_exists 'admin/application_settings/pendo'

app/views/layouts/_head.html.haml

@@ -90,4 +90,4 @@
   = render 'layouts/google_analytics' if extra_config.has_key?('google_analytics_id')
   = render 'layouts/piwik' if extra_config.has_key?('piwik_url') && extra_config.has_key?('piwik_site_id')
   = render 'layouts/snowplow'
-  = render 'layouts/pendo'
+  = render_if_exists 'layouts/pendo'

spec/views/layouts/_head.html.haml_spec.rb

@@ -92,28 +92,6 @@ describe 'layouts/_head' do
     end
   end
 
-  context 'when pendo is enabled' do
-    it 'adds a pendo initialization snippet with url', :aggregate_failures do
-      allow(Gitlab::CurrentSettings).to receive(:pendo_enabled?).and_return(true)
-      allow(Gitlab::CurrentSettings).to receive(:pendo_url).and_return('www.pen.do')
-
-      render
-
-      expect(rendered).to match('pendo.initialize')
-      expect(rendered).to match('www.pen.do')
-    end
-  end
-
-  context 'when pendo is not enabled' do
-    it 'do not add pendo snippet' do
-      allow(Gitlab::CurrentSettings).to receive(:pendo_enabled?).and_return(false)
-
-      render
-
-      expect(rendered).not_to match('pendo.initialize')
-    end
-  end
-
   context 'when a Piwik config is set' do
     let(:piwik_host) { 'piwik.example.com' }