Bug 29604: Dont add psuedo content to highlighted terms

Bug 29604: Dont add psuedo content to highlighted terms

To test:
1. Do a search for something where the search terms will be in the 505
   note.
2. Visit the OPAC detail page of the record.
3. The first occurance of the term highlighting will include the CSS
   pseduo element "→ ";
4. Apply patch
5. Do the stuff to regenerate the CSS
   (https://wiki.koha-community.org/wiki/Working_with_SCSS_in_the_OPAC_and_staff_interface)
6. Do 1 & 2 again.
7. No weird psuedo element in the term highlighting

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>