Bug 9180: All branches should be returned if a default rule exists

Bug 9180: All branches should be returned if a default rule exists

The C4::Overdues::GetBranchcodesWithOverdueRules routine has a bug.
If a default rule *and* a specific rule exist, only the branchcode for
the specific rule is returned.

Test plan:
prove t/db_dependent/Overdues.t
and verify the unit tests are consistent.

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>