The information was previously kept heap-global but is really only
used by spaces when refilling their LABs.

Bug: v8:12615
Change-Id: Iee256d35ffa0112c93ec721bc3afdc2881c4743b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3465898Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79122}