Rename Adyen HPP to Alternative payment methods

Remove functions and settings related to
- payment_selection_on_adyen
- payment_routine
- skin_code
- hmac_test
- hmac_live
- ignore_second_address_field
- delivery_days
at Adyen HPP

Update fall back notes at pay by mail settings

Block/Redirect/Redirect.php

@@ -155,7 +155,6 @@ class Redirect extends \Magento\Payment\Block\Form
         $url = "";
         try {
             if ($this->_order->getPayment()) {
-                $paymentRoutine = $this->_adyenHelper->getAdyenHppConfigData('payment_routine');
 
                 switch ($this->_adyenHelper->isDemoMode()) {
                     case true: