Put some flaky specs in quarantine

Signed-off-by: Rémy Coutable <remy@rymai.me>

ee/spec/requests/api/namespaces_spec.rb

@@ -266,7 +266,7 @@ describe API::Namespaces do
 
     context 'when authenticated as an admin' do
       context 'when namespace is not found' do
-        it 'returns a 404 error' do
+        it 'returns a 404 error', :quarantine do
           do_put(1111, admin, params)
 
           expect(response).to have_gitlab_http_status(404)

spec/features/admin/admin_users_spec.rb

@@ -34,14 +34,11 @@ describe "Admin::Users" do
       expect(page).to have_button('Delete user and contributions')
     end
 
-    describe "view extra user information", :js do
-      it 'does not have the user popover open' do
+    describe "view extra user information" do
+      it 'shows the user popover on hover', :js, :quarantine do
         expect(page).not_to have_selector('#__BV_popover_1__')
-      end
 
-      it 'shows the user popover on hover' do
         first_user_link = page.first('.js-user-link')
-
         first_user_link.hover
 
         expect(page).to have_selector('#__BV_popover_1__')

spec/services/merge_requests/merge_to_ref_service_spec.rb

@@ -104,7 +104,7 @@ describe MergeRequests::MergeToRefService do
         it_behaves_like 'MergeService for target ref'
       end
 
-      context 'when merge commit with squash' do
+      context 'when merge commit with squash', :quarantine do
         before do
           merge_request.update!(squash: true, source_branch: 'master', target_branch: 'feature')
         end