Bug 13879: Fix sort on patron search (guarantor and linked to orders)

Bug 13879: Fix sort on patron search (guarantor and linked to orders)

This patch fixes a regression introduced by bug 13021.

Test plan:
1/ Go on a child detail page > edit
2/ Click on "Set a patron" as a guarantor
3/ Launch a search a confirm that you are able to sort on card, name and
date of birth.
Note that the Address column is not sortable (it's a limitation, could
be fixed later).
4/ Go on the acquisition module, create an order.
5/ Click on the "Add user" button.
6/ Launch a search a confirm that you are able to sort on card, name and
category

Without patch, I could not sort on names. With patch, sorting works as dexcribed in Test plan

Signed-off-by: Marc Veron <veron@veron.ch>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>