Bug 19821: Use database_test entry if exists

Bug 19821: Use database_test entry if exists

If the database_test entry exists in the config file we are going to use
it. This will be a trick for developers and CI

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Bouzid Fergani <bouzid.fergani@inlibro.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>