This reverts commit 4ad20bff.

Reason for revert: New test seems to be failing on TSAN/incremental marking stress (https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20TSAN%20-%20stress-incremental-marking/6346/overview)

Original change's description:
> heap: Fix the tracing of GC cycles
>
> Conceptually, a full GC cycle completes when the sweeping phase is
> finished. As sweeping is performed concurrently, this happens after
> Heap::CollectGarbage has returned and, at the latest, before the next
> full GC cycle begins. However, an arbitrary number of young GC cycles
> may happen in the meantime. Tracing information for the sweeping phase
> must be added to the corresponding full GC cycle event. Until now, this
> was not done correctly: this information was added to the GCTracer's
> current event and could thus be attributed to a subsequent young or full
> GC cycle.
>
> This CL introduces methods GCTracer::(Start|Stop)Cycle to delimit a
> cycle (still allowing for full GC cycles to be interrupted by young GC
> cycles). These methods are different from (Start|Stop)ObservablePause,
> which delimit the observable pause of each GC. The events of "pending"
> full GC cycles are kept until they are properly amended and reported,
> when the sweeping phase is finished.
>
> Bug: chromium:1154636
> Change-Id: I2fbc65d4807c78656d4abc8c451043f6f86211b1
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3404733
> Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Omer Katz <omerkatz@chromium.org>
> Commit-Queue: Nikolaos Papaspyrou <nikolaos@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#78905}

Bug: chromium:1154636
Change-Id: Id6688cfe982f9d8159c66d715b7079782a371bed
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3431489
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Owners-Override: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78908}