Bug 33011: Fix capitalization for "Show in Staff interface?"

Bug 33011: Fix capitalization for "Show in Staff interface?"

This fixes another previously missed occurence.

To test:
* Activate SavedSearchFilters system preference
* Search anything and save your search as a filter from
  the staff interface results page
* Go to Administration > search filters
* Click 'Edit search' for your saved filter
* Confirm you are taken to advanced search page
* On top of the page, you'll see: Show in Staff interface?
* Apply patch
* Verify the string was corrected

Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>