Bug 18991: Fix cleanup in t/db_dependent/Log.t

Bug 18991: Fix cleanup in t/db_dependent/Log.t

There is an action_logs entry via logaction() without transaction to be rolled
back in t/db_dependent/Log.t. This leaves an entry in action_logs after
the test is over.

To replicate:
1. prove t/db_dependent/Log.t
2. Observe a new entry in action_logs table

To test:
1. Apply patch
2. prove t/db_dependent/Log.t
3. Observe there are no new entries in action_logs

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>