Quarantine a broken spec

See https://gitlab.com/gitlab-org/gitlab/-/issues/280554.
Signed-off-by: Rémy Coutable <remy@rymai.me>

spec/support/shared_examples/boards/multiple_issue_boards_shared_examples.rb

@@ -48,7 +48,7 @@ RSpec.shared_examples 'multiple issue boards' do
       expect(page).to have_button('This is a new board')
     end
 
-    it 'deletes board' do
+    it 'deletes board', quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/280554' do
       in_boards_switcher_dropdown do
         click_button 'Delete board'
       end