Bug 9394: Use reserve_id where possible

Bug 9394: Use reserve_id where possible

This patch switches from using a combination of
biblionumber/borrowernumber to using reserve_id where possible.

Test Plan:
1) Apply patch
2) Run t/db_dependent/Holds.t

Signed-off-by: Maxime Pelletier <maxime.pelletier@libeo.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>