Add test case to verify SparkJob completed exceptionally

```python
class SparkJob(ProcessorJob):
"""Represent a Spark job."""

def __init__(
self,
job_future: Future,
) -> None:
super().__init__()
self._job_future = job_future

# TODO: Add test case to verify this method's behavior when job future
# is completed exceptionally.
def cancel(self) -> Future:
cancel_future: Future = Future()
job_future_callback = self._get_job_future_callback(cancel_future)
self._job_future.add_done_callback(job_future_callback)
return cancel_future
```

Start at SparkJob.cancel and inspect the existing SparkJob tests and _get_job_future_callback behavior. Add a test covering an exceptionally completed job future, then run the relevant Python test suite and confirm the returned cancel future reflects the expected exceptional result.

Written by the indexing model from the issue text.