To reproduce
============

- Create one french company and one italian company with their respective localization packages.
- Go to the French company and create a contact, first set the country and then the VAT.
An error message will appear referring to Codice Fiscale but this information is not relevant on the French Company.

Purpose
=======

The VAT field has an onchange trigger `_l10n_it_onchange_vat`  to set `l10n_it_codice_fiscale` value.
on `_l10n_it_onchange_vat` there is no verification if the VAT number is Italian, so we try to get
a Codice Fiscale from it, which leads to error if the VAT number is not Italian.

Specification
=============

To solve the issue we added a verification on the VAT number to make sure that it is an Italian one before
trying to get Codice Fiscale from it.

opw-2777519

closes odoo/odoo#87603

Signed-off-by: Josse Colpaert <jco@odoo.com>