This is a reland of 2a8e2a9b

Original change's description:
> heap: Use generic flags for main-thread only flags
>
> BasicMemoryChunk flags should only be mutated from the main thread
> when no concurrent task can access them. For that purpose it is enough
> to use regular non-atomic flags as they are immutable while the GC is
> running.
>
> Change-Id: I0a9f8ecb2eb2aafaf17e77626ae27604abd1b618
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3107230
> Reviewed-by: Hannes Payer <hpayer@chromium.org>
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#76471}

Change-Id: Iaf495546f82291ab674537f5d39e10d0495ac612
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3117486
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76506}