Bug 18010: Unit test for gettemplate

Bug 18010: Unit test for gettemplate

A trivial test, similar to the ones in Auth.t.
Without the check in gettemplate (added in the second patch), the passwd
file will be exposed and the test fails.

Test plan:
Run t/db_dependent/Templates.t without second patch. The two tests in the
last subtest should fail.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan A Gallagher <brendan@bywatersolutions.com>