There's a flaky test creating a group for a budget which takes place
because toggling a form using jQuery sometimes results in the button not
being correctly clicked by Capybara.
Checking the page with `expect(page).to have_button 'Create group'`
before clicking the button doesn't solve the problem; it looks like in
those cases Capybara waits for AJAX requests but not for JavaScript
animations.
See also issue #2573.