The helper function removes a register from the list and returns it

Bug: v8:7700
Change-Id: I3f9fe9d30113b9e6c7362dc8443e39ae3d1adf07
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3488372Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79284}