This reverts commit a31e8f24.

Reason for revert: Causes DCHECK failures with --stress-snapshot

Original change's description:
> [sandbox] Forbid double-initialization of ExternalPointerSlots
>
> Double initialization may cause the ExternalPointerTable compaction
> algorithm to behave non-optimally: Consider the case of an Entry E1 that
> is owned by a HeapObject O and is marked for evacuation during GC
> marking. In that case, a new entry E2 is allocated for it, and during
> sweeping, E1 will be evacuated into E2 and the Handle in O updated to
> point to E2. However, if a new entry E3 for O is allocated before
> sweeping, then during sweeping E3 (instead of E1) will be moved into E2.
> This may then violate the invariant that the compaction algorithms
> always evacuates an entry out of the evacuation area.
>
> This CL therefore forbids double initializaiton of external pointer
> slots and adds DCHECKs to attempt to catch these in debug builds.
>
> Bug: v8:10391
> Change-Id: I128dc930e8b3f863dab18ba648f34d68d8cb276b
> Cq-Include-Trybots: luci.v8.try:v8_linux64_heap_sandbox_dbg_ng,v8_linux_arm64_sim_heap_sandbox_dbg_ng
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3856563
> Reviewed-by: Igor Sheludko <ishell@chromium.org>
> Commit-Queue: Samuel Groß <saelo@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#82729}

Bug: v8:10391
Change-Id: I37e6728cc16fe79fa7d743417dc9938d58fb0474
Cq-Include-Trybots: luci.v8.try:v8_linux64_heap_sandbox_dbg_ng,v8_linux_arm64_sim_heap_sandbox_dbg_ng
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3857422
Commit-Queue: Samuel Groß <saelo@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#82732}