Wp-calypso: Checkout: G Suite extra licenses should not ask for contact information

[sirbrillig]

We only ever need customer information when creating a brand new G Suite account, not when adding extra licenses.

Reported by @stephanethomas in https://github.com/Automattic/wp-calypso/pull/45737

[michaeldcain]

@stephanethomas: can you explain what information we _should not_ be asking for? The postal code and country from this screenshot are required billing fields for taxes.

[stephanethomas]

Ha, I didn't realize that the postal code and country were required for billing purposes. However, when you click on the Edit link we also ask for the alternate email address as well as the first and last names:

Again we don't need any information from this form in order to provision an extra license, so unless it's required for taxes or anything related to billing I would suggest removing it.

[nbloomf]

Here's a wild idea - the logic for determining what contact form to show in checkout is not trivial, a little scattered, and depends (mostly? entirely?) on business logic involving the cart contents. Can this decision be made on the backend and passed to calypso as a property on the shopping cart endpoint response?