Bug 34094: (follow-up) Fix failing unit test

Bug 34094: (follow-up) Fix failing unit test

The unit tests were written to assume we always do a 'contains' search,
but the new system preference allows for 'starts_with' or 'contains'.

As such, for the tests to pass, we need to explicitly mock the
preference to 'contains'

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit b787e66fef1f14440aa24685171d386bc41b666d)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit 26e4866c9dbff7758bb3e9886f37a002eea6d9e9)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>