Switching payment processors with modified province does not set the province properly

What is happening

Basically, if you are on a Contribution page and click on the Country link for Billing to change the Country and province it will modify for the main Payment method. If you then click another Payment method the billing block reloads, and while the country is changed the province is not

What do you expect to happen

That the province would also change

Potential fixes

I checked and it seems like the ```country_field.val(country_id).trigger("change");``` is not enough. It's like we need to call the CRM call that happens when someone makes a change to the Select2 to basically trigger a change. If you debug the process you will see that setting the province ID fails I believe because the actual provinces aren't loaded yet so the ID is invalid.

Maybe in the backed there is a better strategy instead of using Jquery I don't know.

cc @bgm