Apple currently objects to cleanupSome but agrees to shipping the rest
of WeakRefs. Separate out cleanupSome to its own flag so the rest of
WeakRefs may ship.

Bug: v8:8179
Change-Id: I6159fc743c9cb658860d4260b0dcb95e54630fdc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2141011
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Sathya Gunasekaran  <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67070}