This reverts commit b16c7e5b.

Reason for revert: Suspect for lots of crashes on GPU bots, e.g.:
https://ci.chromium.org/p/v8/builders/ci/Mac%20V8%20FYI%20Release%20(Intel)/11228
https://chromium-swarm.appspot.com/task?id=4f88d01781db5a10

Original change's description:
> Reland "[Heap]: Convert Sweep to Job"
>
> This is a reland of 795c0b1c
> Reason for revert:
> TSAN failures https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN/33884
> Safe to reland as-is with fix to EagerUnmappingInCollectAllAvailableGarbage
> https://chromium-review.googlesource.com/c/v8/v8/+/2502809
>
> Original change's description:
> > [Heap]: Convert Sweep to Job
> >
> > max concurrency is inferred from queue size for OLD_SPACE & MAP_SPACE.
> > Extra Sweeper::TearDown() in MarkCompactCollector::TearDown() is needed
> > to cancel job.
> >
> > Change-Id: Iafba7d7d24e8f6e5c5a1d5c0348dea731f0ac224
> > Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2480783
> > Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
> > Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#70767}
>
> Change-Id: Id9a5baceed4664f53da39597af56a2067e4f3c6f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2502808
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70845}

TBR=ulan@chromium.org,etiennep@chromium.org

Change-Id: Id6e9fe99f016652dd0fedbdbf65662f8e02ed67a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2505974Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70859}