Bug 19108: (follow-up) Fix Stored XSS in fieldmapping.pl and items_search_fields.pl

Bug 19108: (follow-up) Fix Stored XSS in fieldmapping.pl and items_search_fields.pl

To test:
- Add a framework with script in the description
- Access the Keywords to MARC mapping page
- Add an item search field where both name and label are script
- Try to edit/delete the added mapping

With the patch no script should be executed and everything
should still work ok.

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