Change building of the the request for the use case - don't use individual setters for payment data (amount, interval, payment type, iban, etc). Instead, build a PaymentCreationRequest and set it.
Remove all branching that checks the payment type of the returned donation (from the use case response). Instead, do the following:
* if the URL in the response is not null, redirect to it
* otherwise, redirect to the URL of the confirmation page.
Remove URL generators from the fundraising application repo (if possible, they might still be needed by memberships).
Add E2E tests for amounts that are too high or to low, to test that the factory initializes the correct domain specific payment validator (`DonationPaymentValidator`). We removed the tests during {T304729}, because we inverted the dependency and can only test it in an integration test in the Fundraising App.