Tests that use SimulateFullSpace and SealCurrentObjects do not work
if there is a background thread allocating concurrently.

Bug: v8:10315
Change-Id: I73a4c9db8eb32fdf3e07fcb8f5dda309de797709
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2390765Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69693}