This reverts commit 5a6c7dee.

Reason for revert: Speculative: Lots of Chrome crashes:
https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Blink%20Linux/13353/overview

Original change's description:
> cppgc: Fix CTP for destruction
>
> This avoids a benign race in setting the raw pointer inside CTP
> destructor by not emitting the write at all. The handle is destructed
> which means that we only need to destroy any backing node but may
> leave the handle untouched.
>
> Drive-by:
> - Add a few more docs.
> - Make Clear() thread-safe.
> - Make assignment of a sentinel pointer thread-safe.
> - Make assignment of a nullptr thread-safe.
>
> Bug: chromium:1242795
> Change-Id: I0d9dafa31c298053e87ba1eb75f99fa6e33fa10b
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3114134
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Anton Bikineev <bikineev@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#76455}

Bug: chromium:1242795
Change-Id: Ia96d66f4908894091a4e498116d9568bd7b0e0a3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3114058
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76482}