This reverts commit 31d8ff7a.

Reason for revert: https://crbug.com/v8/10190

Original change's description:
> [weakrefs] Schedule FinalizationGroup cleanup tasks from within V8
> 
> Deprecate the following explicit FinalizationGroup APIs in favor of
> automatic handling of FinalizationGroup cleanup callbacks:
>   - v8::Isolate::SetHostCleanupFinalizationGroupCallback
>   - v8::FinaliationGroup::Cleanup
> 
> If no HostCleanupFinalizationGroupCallback is set, then
> FinalizationGroup cleanup callbacks are automatically scheduled by V8
> itself as non-nestable foreground tasks.
> 
> When a Context being disposed, all FinalizationGroups that are
> associated with it are removed from the dirty list, cancelling
> scheduled cleanup.
> 
> Bug: v8:8179
> Change-Id: Ic09313a11dd00af36d1f698250b3d735155f45e8
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1986392
> Commit-Queue: Shu-yu Guo <syg@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#66184}

TBR=ulan@chromium.org,rmcilroy@chromium.org,syg@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: v8:8179
Change-Id: If7869e9a5841803c10e748691f019a7d28f3b62e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2043807Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66190}