DropGraves() is only used to drop gravemarks after a tombstone
removal. Thus, it makes sense to do Inhume() and DropGraves() in one
transaction. It has less overhead and no unexpected problems in case
of sudden power failure.
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
EC parent and split gc marks should be deleted after last EC chunk delete.
Also should delete split info for EC parent and split parent.
Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>