[FIX] hr_holidays: remove stress days for access rights test

The access rights tests would fail on databases created on day 0 and
test executed on day 1 because of the stress day demo data, they would
overlap.

Testing for stress days' access rights are done in dedicated tests, thus
it's ok to delete all the existing ones here.

closes odoo/odoo#112266

Signed-off-by: Kevin Baptiste <kba@odoo.com>