Bug 19361: (QA follow-up) Make sure translatable string is wrapped in double quotes

Bug 19361: (QA follow-up) Make sure translatable string is wrapped in double quotes

This fixes the QA script complaint:

 FAIL	koha-tmpl/intranet-tmpl/prog/en/includes/cateditor-ui.inc
   FAIL	  forbidden patterns
		forbidden pattern: simple-quote string (line 125)

Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit e0880ed3c93a07a999efab85ff18d305a158a893)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>