Move greeting handling up as it is not paymentValidation dependent

[eileenmcnaughton]

Overview

Re-orders validation rules on the event registration form so that the validation for greetings is not after the early return

Before

Validation of greetings is at the end - for zero amount submissions it is never reached

After

Validation is before the early return statement

Technical Details

This is more logical & helps with other code fixes. However, I could be talked into just removing the validation. If feels like something that could be somewhat easily misconfigured & missing the custom value would be less bad than losing the form submission

Comments

[civibot]

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