S3FileTransformOperator logs stdout of the underlying process as such:
While stderr is omitted entirely, unless exit code is not 0 (in this case it's included in the exception message only).
1. Both streams are logged, regardless of the underlying process outcome (i.e. success or failure).
2. Stream output is decoded before logging (e.g. \n is replaced with an actual new line).
3. If transform_script fails, the exception message contains return code of the process.