Bug 18146: Fix tests for OverduesBlockRenewing

Bug 18146: Fix tests for OverduesBlockRenewing

This pref was supposedly covered by tests, but the conditions were wrong
and we didn't test the reasons we were failing so the code was being missed

To test:
1 - Add a warn around in the conditional at line 2748:
} elsif ( ($hasoverdues and $overduesblockrenewing eq 'block') || ($itemissue->{overdue} and $overduesblockrenewing eq 'blockitem') ) {
     warn "SUCCESS!"
     return ( 0, 'overdue');
}
2 - prove -v t/db_dependent/Circulation.t | grep SUCCESS
3 - No output
4 - Apply patch
5 - Repeat
6 - SUCCESS!

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>