Merge branch 'sh-fix-flaky-subscription-spec' into 'master'

Fix flaky user_manages_subscription_spec.rb

Closes #207835

See merge request gitlab-org/gitlab!26611

spec/features/merge_request/user_manages_subscription_spec.rb

@@ -16,6 +16,8 @@ describe 'User manages subscription', :js do
 
   it 'toggles subscription' do
     page.within('.js-issuable-subscribe-button') do
+      wait_for_requests
+
       expect(page).to have_css 'button:not(.is-checked)'
       find('button:not(.is-checked)').click