[heap] Remove CHECK in SimulateIncrementalMarking after loop

Concurrent markers could add work into the worklist before the CHECK.

Bug: v8:12775, v8:13223
Change-Id: I8ac252b0fec8e5acbcfec56dad04830e596c709d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3854496
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82690}

test/cctest/heap/heap-utils.cc

@@ -193,8 +193,6 @@ void SimulateIncrementalMarking(i::Heap* heap, bool force_completion) {
   while (!marking->IsMarkingComplete()) {
     marking->AdvanceForTesting(kStepSizeInMs);
   }
-
-  CHECK(marking->IsMarkingComplete());
 }
 
 void SimulateFullSpace(v8::internal::PagedSpace* space) {

test/unittests/heap/heap-utils.cc

@@ -34,7 +34,6 @@ void HeapInternalsBase::SimulateIncrementalMarking(Heap* heap,
   while (!marking->IsMarkingComplete()) {
     marking->AdvanceForTesting(kStepSizeInMs);
   }
-  CHECK(marking->IsMarkingComplete());
 }
 
 void HeapInternalsBase::SimulateFullSpace(