Remove API3 StripePaymentintent.process and StripePaymentintent.createorupdate and other legacy code

Remove exception that causes loading of contribution pages to fail with 'Check Stripe credentials' if live does not have credentials but test does

When form incorrectly submits a one-off for a recur log an error and return a generic error message (it's a configuration error)

Fix recording balancetransaction details (eg. available_on) on FinancialTrxn when payment is completed immediately (eg. Contribution page) and add tests to cover this scenario

smartyv2-1.0.1 does not work on 5.59 because of https://github.com/civicrm/civicrm-core/commit/7168793c03ef57c06bbfe45f5ff873ebb3657806