Market-excluded preorder variants should display as a regular sold-out PDP with Notify Me button

When using market-based preorders, a product may be available for preorder in one market but sold out in another.

Currently, if the same variant is enabled for preorder in another market, it can still appear available in an excluded market even though customers cannot purchase it. The variant option does not appear greyed out like a regular sold-out variant, and the Notify Me button is also not shown.

For markets where preorder is not available, we would like the variant to behave like a normal sold-out product:

• Show the variant option as greyed out/unavailable.

• Show the Notify Me button so customers can sign up for restock notifications.

This is important because otherwise customers may think the variant is available when it is not, while we also lose the opportunity to collect sign-ups.