Don't actually free memory as that would maintain free bytes accounting.
Instead, just write a filler that is reclaimed on next garbage
collection, updating counters.

Bug: v8:13000, chromium:1338687
Change-Id: I5339505160fde4b2f522a1a4212d23d7afc2b5f3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3726292Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81407}