[php8-compat][REF] Fix more php8 test failures caused by template issues

[seamuslee001]

Overview

This adds more fixes for template issues in tests fixing the following test:

• CRM_Financial_Form_PaymentFormsTest::testEventPaymentForms
  Undefined array key "is_refund"

Before

Test failed on php8

After

Test passes on php8

ping @eileenmcnaughton @totten @demeritcowboy

[civibot]

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[demeritcowboy]

I think you need to also update civicrm_generated when message templates change? It looks like they're in there.