Bug 19047: Fix AddBiblio call in Reserves.t

Bug 19047: Fix AddBiblio call in Reserves.t

AddBiblio does not return a title; the biblioitemnumber is stored in the
title variable.
The variables for biblioitemnumber are not used and can be removed.

Test plan:
Run t/db_dependent/Reserves.t

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit c6f8cf69d3943599fa6a0c250ae0e8221ead44ff)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>