Bug 33198: Don't calculate pickup locations per bib unless placing multiple holds

Bug 33198: Don't calculate pickup locations per bib unless placing multiple holds

For single bibs we use an ajax select2 dropdown, and we don't use this
value

To test:
1 - Place some holds on single bibs
2 - Confirm dropdowns for pickup location work as expected
3 - Do the same for multiple bibs selected from search results
4 - Apply patch
5 - Confirm there is no change after the patch

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>