Bug 28891: (bug 23916 follow up) Always use 'Checkout on' as default Checkout history...

Bug 28891: (bug 23916 follow up) Always use 'Checkout on' as default Checkout history sort column

To test:
1 - Unset RecordStaffUserOnCheckout
2 - Check out an item
3 - Display Checkout history, table is sorted by 'Checkout on' column
4 - Set RecordStaffUserOnCheckout
5 - Display Checkout history, table is sorted by 'Renewed' column
6 - Apply patch
7 - Redo 1, 3, 4 and 5, table is always sorted by 'Checkout on'

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