This reverts commit edcc8ff5.

Reason for revert: https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Blink%20Linux%20Debug/10806/overview
A prefinalizer is creating a WeakMember from a raw pointer to a dead object for checking whether it is in a set.

Original change's description:
> cppgc: Enable checks for assignments in prefinalizers
>
> Bug: v8:11749
> Change-Id: Ic027f732030fb6a2befeffeca9db2eacfd0830a5
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3099953
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Commit-Queue: Omer Katz <omerkatz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#76370}

Bug: v8:11749
Change-Id: I0c90f232df9ae363f05f8b9ba26c2a7eede8a269
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3106646
Auto-Submit: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#76377}