Bug 30085: Reduce scope of holds count / today holds count

Bug 30085: Reduce scope of holds count / today holds count

We retrieve two counts that are only needed if rules for hold limits are defined.
The DB counts should only be fetched once the rules are confirmed to exist

Further improvement would be possiblke by allowing them to be passed in (or cached?)
from CanBookBeReserved as they rely only on patron/biblionumber and not item specific information

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>