The deopt-stress mode is unused. This prepares for deprecating
corresponding api methods.

The same kind of testing can be done by using --stress-opt and
setting --deopt-every-n-times.

Bug: v8:9941
Change-Id: I6796fcfa43d0efad51ec9d9a9adc949c26805a81
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1899617Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64772}