Reasons:
 * We disabled it more than a year ago for all configs
 * Not easy to re-enable
 * Not compatible with pointer compression as-is
 * Not compatible with concurrent TP/TF as-is
 * No concrete plans to re-enable it

Also remove Map's layout_descriptor since it was only used for double
field unboxing.

Bug: v8:11422
Change-Id: I9260906eac199213b3210712e9903f1ecf1d7979
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2676637Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72671}