Bug 20006: (follow-up) Fix holds.js

Bug 20006: (follow-up) Fix holds.js

This patch makes holds.js call the endpoint with 'pickup_library_id'
instead of the old 'branchcode' property.

To test:
- Place a hold
- Go to the patron's detail page
- Go to the Holds tab
- Change the pickup location
=> SUCCESS: It works!

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit f6b3d9979dc996dff7bf29fd5747e91695f93d0f)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>