[FIX] l10n_id: adapt the check to the new VAT regulation

The issue:
Currently, in Indonesia, the regulation for tax ID is 15 digits.
But a new regulation is coming where Tax ID is now 16 digits by adding 0 in front

The fix:
Remove the first zero and leave the rest for the _run_vat_test function

Related PR: #146111

opw-3782636

closes odoo/odoo#157885

Signed-off-by: Quentin De Paoli <qdp@odoo.com>

addons/base_vat/models/res_partner.py

@@ -769,7 +769,7 @@ class ResPartner(models.Model):
 
         # VAT is only digits and of the right length, check the Luhn checksum.
         try:
-            luhn.validate(vat[0:9])
+            luhn.validate(vat[0:9] if len(vat) == 15 else vat[1:10])
         except (InvalidFormat, InvalidChecksum):
             return False