insights: make job errors `NonRetryable` where applicable

Created by: leonore

The job worker retries jobs when they are errored if they are not marked as non-retryable: see code.

All the errors we return in our work_handler in insights use some variation of errors.New and would not be classified as non retryable, so there might be some cases where we are repeating logic redundantly as we have encountered unretryable errors.