Rollup merge of #109412 - GuillaumeGomez:add-gui-test, r=notriddle

rustdoc: Add GUI test for "Auto-hide item contents for large items" setting

Part of rust-lang/rust#66181.

The `browser-ui-test` version update is because there wasn't `null` check for attributes so I added it (PR is [here](GuillaumeGomez/browser-UI-test#440)).

r? ``@notriddle``

Author: matthiaskrgr