osd: Clear part of cleaned_meta_map in case of a restarted smaller chunk

osd: Clear part of cleaned_meta_map in case of a restarted smaller chunk

This can not happen at the primary because scrub_compare_maps() is only
called once per chunk start.

Preemption causes a smaller chunk from start to be processed again at
replicas.  We clear any of the previous chunk's information.

Signed-off-by: David Zafman <dzafman@redhat.com>
(cherry picked from commit 9e0ac797c602a088447679b04e14ec0cfaf9dd7b)