On graceful shutdown we will wait for discard queue to drain before storing the alloc...

On graceful shutdown we will wait for discard queue to drain before storing the allocator.
ON fast shutdown we will simply copy the discard queue entries to the allocator

Signed-off-by: Gabriel BenHanokh <gbenhano@redhat.com>
(cherry picked from commit 4762ffaaa19ca2afe8864fa1a6fb67ceea3aa640)