Since odoo/odoo@8c713ed270, we are
not able to use invalid VATs anymore, so we remove the usage of it
in these tests, as it doesn't change the validity of them.
If reusing existing records, there's the risk of conflicting tests, like modifying
the VAT for the existing company and that company having a country with VAT check.
We avoid it creating a new company instead.
Pedro M. Baeza
Carlos Roca
Efren
Enric Tobella