Drive-by fix: The file name for WATCHLISTS in the OWNERS file rule was
wrong, so fixing that too so that it's possible to modify WATCHLISTS
without eng reviewers approval in the future.

Change-Id: I0e24c5d459aab2bb346aca64125eabe0ceac8274
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2903154Reviewed-by: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Patrick Thier <pthier@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74644}