This reverts commit 9e8c54f8.

Reason for revert: Data races (https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20TSAN/33100)

Original change's description:
> [Heap] ScavengerCollector use Jobs.
> 
> No yielding is necessary since the main thread Join()s.
> 
> max concurrency is determined based on either
> remaining_memory_chunks_ or global pool size
> (copied_list_ + promotion_list_)
> 
> Change-Id: Ie30fa86c44d3224b04df5d79569bce126ce7d96b
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2354390
> Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#69746}

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

Change-Id: I206397c6086cf18d5e08cf615bdaaf0f34c6d36b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2398852Reviewed-by: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69748}