Also remove or adapt all mentioning of buildbot. The flag was removed
on the infra side here:
https://crrev.com/c/1827557

Change-Id: I8a6be80faa65f99cd42a084c804fc5bfae7f02c2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1826722Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64017}