os/bluestore/BlueStore::NCB - removed bogus assert for overlapping extents Fixes: https://tracker.ceph.com/issues/52138
BUG-FIX: NCB code was reporting Bogus error when we had an overlapped extent between shared-blobs on the same Onode (which is a legal case)
The error check was refined to skip shared-blobs
I also added an assert for copy-allocator spillover (should never happen) and removed an early exit when an empty extent was found (we report and skip it) Signed-off-by: Gabriel Benhanokh <gbenhano@redhat.com>