This reverts commit d83346be.

Reason for revert: Seems to be breaking TSAN bot (https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20TSAN%20-%20stress-incremental-marking/8867/overview)

Original change's description:
> [test] Migrate cctest/test-weakmaps to unittests/
>
> Bug: v8:12781
> Change-Id: Ief6bd7ee0ff2876e19970b2fb6af4f3208ec7f4e
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3815486
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82699}

Bug: v8:12781
Change-Id: Ia20078e9f40d0e2257cf0b953ddd2e72594c4085
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3855938
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#82713}