Bug 31917: Headings fix for preferences search

Bug 31917: Headings fix for preferences search

This patch re-arranges the logic for displaying the search term when
executing a system preference search.

Test plan
1) Without the patch, search for something that will get no results
   'boing' and note how it looks
2) Without the patch, search for something that gets some results
   'block' and note how it looks
3) Apply the patch
4) Repeat your searches and comment on whether the look is better of
   worse ;P

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>