[FIX] base: correct ISO language code
[FIX] base: correct ISO language code

Bad ISO 639-1 code
In 9.0 iso_code was guessed with `get_iso_codes` which was too simplistic
e.g. it_IT => it (correct) but ja_JP => ja_JP (incorrect)

Fixes tw:tashiropen/status/927779483041415168

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo