StepOrigin is enough to infer the right completion action: Either
finalization by task (for StepOrigin::kTask) or stack guard
(for StepOrigin::kV8).

Only tests with StepOrigin::kV8 were violating this but they also just
pass when enabling the stack guard.

Bug: v8:12775
Change-Id: I5df50198d8e3612ee97142f84bd497820a5cec78
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3816664Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82294}