Ticket 47750 - During delete operation do not refresh cache entry if it is a tombstone
Bug Description: After calling the betxn postop plugins do not attempt to refresh the
entry if it was converted to a tombstone. A tombstone entry does
not have its entry mutex allocated, and it will be dereferenced.
Fix Description: If the entry is converted to a tombstone, there is no need to
refresh it in the first place. Skip the cache refresh if its a
tombstone. If its not a tombstone, we also need to return the
cache entry if it was not changed in betxn postop, because we
incremented its refcnt while checking if it was updated.
Reviewed by: nhosoi(Thanks!)
(cherry picked from commit 4ae67943e807b869aeda213dcd39b59feb5f8259)