#### Description of the issue/feature this PR addresses:
Rating a Starshipit shipment for an incomplete delivery address makes the whole rating loop fail instead of skipping that carrier. This breaks express checkout (Apple Pay / Google Pay), where the wallet only discloses a partial address before authorization: the customer gets "update postal address" and cannot pay, while manual checkout works.

#### Current behavior before PR:
delivery_starshipit is the only connector that rates a shipment without validating the addresses first, and it ignores the express_checkout_partial_delivery_address context key set by website_sale. The empty street is sent to /api/rates, which answers 200 with {"success": false, "errors": [{"details": "street parameter value is required"}]}, and _send_request turns that into a UserError. As starshipit_rate_shipment lets it propagate, it aborts the rating of every carrier instead of only this one, so no delivery method reaches the wallet. The same happens for errors only the api can report, such as invalid credentials.

#### Desired behavior after PR is merged:
Both the recipient and the warehouse address are validated before the api is called, as the other connectors already do, and the message is returned as an unsuccessful rate rather than raised. Starshipit requires the street, so a streetless address is still refused, but with a neutral message in the express checkout flow since the customer cannot complete it before paying. The Starshipit carrier is simply not proposed among the wallet's options, the other carriers are rated normally, and express checkout completes.

opw-6393393

Forward-Port-Of: odoo/enterprise#125117