Bug 26756: Fix quotes showing behind some system preference descriptions

Bug 26756: Fix quotes showing behind some system preference descriptions

This patch adds matching quotes to two OPAC preference descriptions
which were missing them.

To test, apply the patch and go to Administration -> System preferences.

- Open the "OPAC" tab.
- Check the descriptions of these preferences:
  - AllowPatronToSetCheckoutsVisibilityForGuarantor
  - AllowPatronToSetFinesVisibilityForGuarantor

There should be no trailing quotation mark.

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