Remove the "none selected" behavior from the address validation settings

I reviewed this this evening, and perhaps it didn't work before, but it works now. That said, it's a weird place to use this sort of "selecting none applies to all" behavior. There are only two countries, and it should just be treated as enabling. I'm going to convert this to a task to remove this "none" behavior, but it will require an update hook to convert any configuration with none selected to have both selected. For that, I think we can reserve the change for a new major version.