Using separate tests to check every link on the page made the tests
slower. We were also adding a useless initial request on tests which
started by visiting a different URL.
This useless initial request meant in some tests the browser was started
before using factories to create data. Accessing the database in the
test after the browser starts might cause concurrency issues in
JavaScript tests.
Using `<a>` tags with no `href` means these elements cannot be activated
by keyboard users, so we're replacing them with buttons.
In the future we probably want to add more consistency so all toggle
buttons use the same code. We might also add styles depending on the
`aria-expanded` property.
