Remove usage of deprecated paymentProcessorType function

[mattwire]

Overview

This cleans up and removes usage of deprecated CRM_Core_PseudoConstant::paymentProcessorType in favour of standard getKey/getName functions. Duplicated code from getPayment is also removed and consolidated into a single function.

Before

Duplicated code and usage of deprecated function.

After

Removed duplicated code and usage of deprecated function.

[mattwire]

This came out of work done on #12007

[eileenmcnaughton]

test this please

[eileenmcnaughton]

In fact this whole chunk seems to do nothing?

    if (!empty($fields['is_recur_interval'])) {
      foreach (array_keys($fields['payment_processor']) as $paymentProcessorID) {
        $paymentProcessorTypeId = CRM_Core_DAO::getFieldValue(
          'CRM_Financial_DAO_PaymentProcessor',
          $paymentProcessorID,
          'payment_processor_type_id'
        );
        $paymentProcessorType = CRM_Core_PseudoConstant::paymentProcessorType(FALSE, $paymentProcessorTypeId, 'name');
      }
    }

[eileenmcnaughton]

I read through this pretty carefully & I'm confident the change is as intended & it is just a simplification. I stepped through the code results for getPayment in a debugger from submitting a back office participant record & it seemed fine

[seamuslee001]

Jenkins retest this please