Similar to full GCs, the GC defers metric reporting until sweeping is
finished.

Bug: chromium:1029379
Change-Id: Ib06adb3be691c1ad2bd530eb77fc01cc22537338
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3576130Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Nikolaos Papaspyrou <nikolaos@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79891}