Select subscription's credit card automatically in credit card update

[ae-mo]

That solves the hangup, but now it shows the cards used for each subscription, even if they are the same card, which is confusing. Maybe we could filter out duplicates? Well, that might not be possible due to Nets. But maybe data on which card is tied to which subscription?

Originally posted by @mfahler9 in https://github.com/KSF-Media/affresco/issues/559#issuecomment-792878749

We should select the credit card tied to a subscription when we want to update its credit card.