LP#2023338: Correct BHSSO selection_depth sort

LP#2023338: Correct BHSSO selection_depth sort

Before customizable Best Hold Selection Sort Order was implemented, the
non-FIFO hold order considered more-constrained holds before
less-constrained ones on the assumption that there would be more copies
available to less-constrained ones.  That ordering didn't make it into
the BHSSO implementation, so this commit corrects that by sorting this
part in descending selection depth order rather than the default
ascending.

This is not relevant in most cases, but when soft hold boundaries are
used, and during the transition from a non-resource-sharing to a
resource-sharing enviroment, it can have an effect if "depth" is
selected as a BHSSO component.

Signed-off-by: Mike Rylander <mrylander@gmail.com>
Signed-off-by: Terran McCanna <tmccanna@georgialibraries.org>