We don't actually ever need the MaglevCompiler instance.

Bug: v8:7700
Change-Id: I876353310cf34971b72b08d2113d87caaa255e13
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3585957
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Commit-Queue: Jakob Linke <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79987}