This fixes a flaky crash when running with --turbo-stats or
--turbo-stats-wasm.
With dynamic tiering, it can happen that a compilation job is started
shortly before the program/test/benchmark terminates and the main thread
goes through its teardown sequence. When such a late job finishes, it
still wants to report its statistics, which currently crashes due to
UAF if the CompilationStats object, which is owned by the main thread,
has already been deleted.

Change-Id: Ie25a97299fdf40ece8f286487063feadcfa2eea9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3645410
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80560}