Reland^2 "Batch compacted pages to reduce number of uffd ioctls."

This reverts commit c655cdc973087e8357e6aa388cbb1b0e737b69e6.

Reason for revert: Fixing issues with linear-alloc compaction.

If some pages are being processed by some mutator(s) within the
arenas that gc-thread tries to madvise, then it causes heap corruption.
In such case we need to avoid madvise until the mutator(s) are finished.

Bug: 320478828
Bug: 160737021
Test: manual
Change-Id: Ia182a276049c0e0d3c080648059c186a1880c982