Bug 18255: Koha::Biblio - Replace GetBiblioItemByBiblioNumber with Koha::Biblio-...

Bug 18255: Koha::Biblio - Replace GetBiblioItemByBiblioNumber with Koha::Biblio->biblioitem

The subroutine GetBiblioItemByBiblioNumber considers that we have a 1-N
relation between biblio and biblioitems, which is wrong (it's 1-1).
So the calls can be replaced with Koha::biblio->biblioitem, it will ease
the read of the code.

Test plan:
1. Use the ILSDI service to display info of a bibliographic record,
biblioitems fields must be displayed
2. Search for items, biblioitems info must be displayed as well in the
result table

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>