To avoid shrinking the unregister token map on each pop of the cleared
cell list, the Torque implementation of the cleanup loop avoids
shrinking the map until the end of the loop.

To support that, PopClearedCellHoldings is refactored to the Torque
PopClearedCell which calls the
JSFinalization::RemoveCellFromUnregisterTokenMap and the runtime
ShrinkFinalizationRegistryUnregisterTokenMap. The former cannot GC is
and is implemented in CSA as a fast C call. The latter can GC and is a
runtime call.

This also incidentally makes uses of FinalizationRegistry without
unregister token a fast path that doesn't have to leave Torque.

Bug: v8:8179
Change-Id: Ia0c3c5800d26e31319a818f164f6bd3267355aa6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2137950
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67161}