Use correct code for Greece VAT validation

[elidrissidev]

Description (*)

Greece uses a different code for VAT validation number (EL) than its ISO-2 country code (GR). This PR backports the fix in magento2 to allow overriding the country code before performing the VAT validation request.

Related Pull Requests

• See Fixes incorrect country code being used for Greek VAT numbers, should… magento/magento2#20548

Fixed Issues (if relevant)

1. Fixes VAT validation for greek VAT IDs always fails #2828

Manual testing scenarios (*)

1. Create a customer with Greece country in its address, then try validating the VAT number either from the frontend or admin.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All automated tests passed successfully (all builds are green)
• Add yourself to contributors list

[fballiano]

amazing