Remove inappropriate exception handling.

Remove inappropriate exception handling.

Per discussion in https://github.com/civicrm/civicrm-core/commit/570243c292fa7bceea74ce233feceb3f69211e54#r31805899

the core logic has been changed to now accept a payment regardless of contribution status. This reflects the
fact that a payment could be received for a fully paid contribution and we still need to record it.

This exception is inappropriately narrow (& likely in the wrong place since it should probably be closer to
where the decision is made about adding a payment rather than when it is being processed