Make phone number field optional for trial form

Runs an experiment with making the phone number field optional within
SaaS trial sign up behind a feature flag

ee/app/views/trials/new.html.haml

 - page_title _('Start your Free Gold Trial')
 - glm_params = { glm_source: params[:glm_source], glm_content: params[:glm_content] }
+- phone_number_required = Feature.disabled?(:trial_form_phone_optional, current_user)
+- phone_number_label = phone_number_required ? _('Telephone number') : _('Telephone number (Optional)')
 
 %h3.center.pt-6
   = _('Start your Free Gold Trial')
@@ -23,8 +25,8 @@
     = label_tag :company_size, _('Number of employees'), for: :company_size, class: 'col-form-label'
     = select_tag :company_size, company_size_options_for_select(params[:company_size]), include_blank: true, class: 'select2', required: true
   .form-group
-    = label_tag :phone_number, _('Telephone number'), for: :phone_number, class: 'col-form-label'
-    = text_field_tag :phone_number, params[:phone_number], class: 'form-control', required: true
+    = label_tag :phone_number, phone_number_label, for: :phone_number, class: 'col-form-label'
+    = text_field_tag :phone_number, params[:phone_number], class: 'form-control', required: phone_number_required
   .form-group
     = label_tag :number_of_users, _('How many users will be evaluating the trial?'), for: :number_of_users, class: 'col-form-label'
     = number_field_tag :number_of_users, params[:number_of_users], class: 'form-control', required: true, min: 1

ee/spec/features/trials/capture_lead_spec.rb

@@ -12,12 +12,38 @@ describe 'Trial Capture Lead', :js do
   end
 
   context 'when user' do
+    let(:trial_form_phone_optional_feature_enabled) { false }
+
     before do
+      stub_feature_flags(trial_form_phone_optional: trial_form_phone_optional_feature_enabled)
+
       visit new_trial_path
 
       wait_for_requests
     end
 
+    context 'phone number is optional' do
+      let(:trial_form_phone_optional_feature_enabled) { true }
+
+      context 'without phone number' do
+        it 'proceeds to the next step' do
+          expect_any_instance_of(GitlabSubscriptions::CreateLeadService).to receive(:execute) do
+            { success: true }
+          end
+
+          fill_in 'company_name', with: 'GitLab'
+          select2 '1-99', from: '#company_size'
+          fill_in 'number_of_users', with: '1'
+          select2 'US', from: '#country_select'
+
+          click_button 'Continue'
+
+          expect(page).not_to have_css('flash-container')
+          expect(current_path).to eq(select_trials_path)
+        end
+      end
+    end
+
     context 'enters valid company information' do
       before do
         expect_any_instance_of(GitlabSubscriptions::CreateLeadService).to receive(:execute) do

locale/gitlab.pot

@@ -20207,6 +20207,9 @@ msgstr ""
 msgid "Telephone number"
 msgstr ""
 
+msgid "Telephone number (Optional)"
+msgstr ""
+
 msgid "Template"
 msgstr ""