This reverts commit ea818f07.

Reason for revert: Test failure in Linux64 UBSan https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20UBSan/15251/overview

Original change's description:
> cppgc: Fix testing APIs that enable garbage collection
>
> The APIs require that the CppHeap is moved into a permanently detached
> state that moves the heap out of a no-gc scope.
>
> Bug: chromium:1056170
> Change-Id: I1fc08451b3fdfaa4cfe58e6a1ddbe5dbed7efe5c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2718146
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Omer Katz <omerkatz@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#73025}

Bug: chromium:1056170
Change-Id: Id00cb18274cbe7d255e7e95bd9e8e4dbc4b0c6e7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2718658
Auto-Submit: Zhi An Ng <zhin@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Francis McCabe <fgm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73029}