In the future we may want to cache this in a separate slot to turbofan
code, but for now cache maglev code in the same optimized code slot on
the feedback vector.

Bug: v8:7700
Change-Id: Idd40a024cc9beb9b4da06a88a3789d822ddd4ab7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3622916Reviewed-by: Jakob Linke <jgruber@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80354}