Bug 20596: Add unit test for multiple values in authority search

Bug 20596: Add unit test for multiple values in authority search

This patch adds a unit test which returns 2 authority records
via an implicit OR when searching for strings from two different
authority records.

Test plan:
1. prove t/db_dependent/Search.t

Signed-off-by: Jan Kissig <jan.kissig@th-wildau.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 76d676a868be048ec57c8eb178bf813a12823c6e)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>