Fix some issues with nested suspenders:
- Fix scratch register conflict when returning from an inner suspender
- The outer suspender should stay in 'Active' state
- Suspenders should become 'Inactive' when they return

CC=ahaas@chromium.org

Bug: v8:12191
Change-Id: Ic6c6108c4f8df3d32417d7813eb04e0e2a46d27a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3743386Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81555}