Bug 13451: Holidays.t assumes default data

This patch removes that assumption by expressly setting data
to be default.

TEST PLAN
---------
1) Ensure that branch code is NOT 'MPL' in the
   repeatable_holidays table in your database.
2) Ensure that branch codes 'MPL' and 'CPL' do not exist
   in the branches table in your database.
3) prove t/db_dependent/Holidays.t
   -- this should bomb horribly.
4) Apply patch
5) prove t/db_dependent/Holidays.t
   -- all tests should succeed.
6) run koha qa tests

Signed-off-by: Nick Clemens <nick@quecheelibrary.org>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Tests pass without holidays in the calendar.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
(cherry picked from commit d37dee3ddf97a028cc42ef15fd9f938d9b7bd89a)
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>