os/bluestore: Added checks for compacting BlueFS log for flush and fsync ops

os/bluestore: Added checks for compacting BlueFS log for flush and fsync ops

This partially fixes https://tracker.ceph.com/issues/45903

Signed-off-by: Adam Kupczyk <akupczyk@redhat.com>
(cherry picked from commit fab0c7148e84b1612e8e422e1876643a7cd4070b)

Conflicts:
	src/os/bluestore/BlueFS.cc
- commits are being backported to octopus in the wrong order:
  7b01af4d95bfa789b3b3247d016431fdbfd844a4 went into master before this commit,
  yet it has already been backported to octopus
	src/os/bluestore/BlueFS.h
- dropped duplicate _maybe_compact_log declaration added by
  c4312689ab7d32239d8b91684e3f57e9c032ea2f in favor of the one from
  master added by fab0c7148e84b1612e8e422e1876643a7cd4070b