Bug 30756: Further adjustments to Koha_Authority.t

Bug 30756: Further adjustments to Koha_Authority.t

Remove use of exported_records file in favor of TestBuilder.
Remove conditional tests with SKIP block. Create reservoir record.

Test plan:
Run t/db_dependent/Koha_Authority.t

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>