Revert "Revert "Move most of NFS file handle affinity code out of the heavily congested""

This reverts commit 20b267a3c12655c166478f3852ffd464066abadf.

Reverting a revert. Priceless.
Add a missing lock.

Ticket: #4052
Merge remote-tracking branch 'origin/feature/unified_freebsd' into feature/hyperv