Shut down temporary ChromeDriver instances

Some ChromeDriver integration tests create temporary ChromeDriver
instances. With this commit we make sure that these instances are
terminated as quickly as possible when they are no longer needed.

Bug: 375974725
Change-Id: I0306caaf60b2b0ea7e62d8d9339f8d65ce2fcf10
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5997970


Auto-Submit: Vladimir Nechaev <nechaev@chromium.org>
Commit-Queue: Maksim Sadym <sadym@chromium.org>
Reviewed-by: Maksim Sadym <sadym@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1378884}