Bug 17664: Silence non-zebra warnings in t/db_dependent/Search.t

Bug 17664: Silence non-zebra warnings in t/db_dependent/Search.t

TEST PLAN
---------
0) back up database
1) drop database; create database
2) run web installer
3) prove t/db_dependent/Search.t
   -- the spammy warnings (other than zebra index warnings) may
      already be fixed, but the mocked value was not realistic.
4) apply patch
5) prove t/db_dependent/Search.t
   -- notice only zebra index warnings.
6) run qa test tools

Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>