Add tracking to clicking buy ci minutes

- track

ee/app/views/layouts/header/_buy_ci_minutes.html.haml

 - return unless show_buy_ci_minutes?
 
 %li
-  = link_to profile_pipeline_quota_path, class: 'ci-minutes-emoji' do
+  = link_to profile_pipeline_quota_path,
+    class: 'ci-minutes-emoji',
+    data: { 'track-event': 'click_buy_ci_minutes', 'track-label': current_user.namespace.actual_plan_name, 'track-property': 'user_dropdown' } do
     = s_("CurrentUser|Buy CI minutes")
     = emoji_icon('clock9', 'aria-hidden': true)

ee/spec/views/layouts/header/_current_user_dropdown.html.haml_spec.rb

@@ -16,7 +16,10 @@ describe 'layouts/header/_current_user_dropdown' do
   subject { rendered }
 
   context 'when ci minutes need bought' do
-    it 'has "Buy CI minutes" link' do
+    it 'has "Buy CI minutes" link with correct data properties', :aggregate_failures do
+      expect(subject).to have_selector('[data-track-event="click_buy_ci_minutes"]')
+      expect(subject).to have_selector("[data-track-label='#{user.namespace.actual_plan_name}']")
+      expect(subject).to have_selector('[data-track-property="user_dropdown"]')
       expect(subject).to have_link('Buy CI minutes')
     end
   end