Bug 19533: Hold pulldown for itemtype is empty if hold placement needs override

Bug 19533: Hold pulldown for itemtype is empty if hold placement needs override

Test Plan:
1) Enable AllowHoldPolicyOverride
2) Enable AllowHoldItemTypeSelection
3) Create a situation where adding a hold for a patron would trigger a tooManyReserves
   warning.
4) Note the itemtype pulldown is empty
5) Apply this patch
6) Reload the page
7) Itemtype pulldown should have values

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>