This reverts commit 7f29c48e.

Reason for revert: Causing TSAN failures on test bots.

Original change's description:
> [heap] Remove sweeping state in incremental marking
> 
> Remove the SWEEPING state from incremental marking. Sweeping is now
> always completed when starting incremental marking. Before this change
> there needed to be a safepoint each for starting marking and completing
> sweeping. Now both happens within a single safepoint.
> 
> Bug: v8:10315
> Change-Id: Iad2835554865f2de24376372affe9a98992d1fa0
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2190419
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#67678}

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

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:10315
Change-Id: I5e76990155cf7aeee3ecefe5e37f9028cb188a00
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2192658Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67699}