qa: krbd_exclusive_option.sh: update for recent kernel changes

qa: krbd_exclusive_option.sh: update for recent kernel changes

Since 5.3:
- a plain "rbd map" acquires the lock, so it's not different from
  "rbd map -o exclusive" in this regard
- if the lock is held by the exclusive peer, I/O is failed right away
  instead of blocking
- lock_timeout option is respected only by "rbd map" and not by I/O

Since 5.5:
- if the mapping is read-only, the lock isn't acquired

Added blacklisting test case, dropped lock_timeout test case.

Fixes: https://tracker.ceph.com/issues/43127
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>