[SPARK-49930][SS] Ensure that socket updates are flushed on exception…

… from the python worker

### What changes were proposed in this pull request?
Ensure that socket updates are flushed on exception from the python worker

### Why are the changes needed?
Without this, updates to the socket from the python worker are not delivered to the jvm side

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
Existing tests were failing on a different Python version and pass after

```
Run completed in 1 minute, 13 seconds.
Total number of tests run: 8
Suites: completed 1, aborted 0
Tests: succeeded 8, failed 0, canceled 0, ignored 0, pending 0
All tests passed.
```

### Was this patch authored or co-authored using generative AI tooling?
No

Closes apache#48418 from anishshri-db/task/SPARK-49930.

Authored-by: Anish Shrigondekar <anish.shrigondekar@databricks.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>

python/pyspark/sql/streaming/python_streaming_source_runner.py

@@ -193,6 +193,8 @@ def main(infile: IO, outfile: IO) -> None:
             reader.stop()
     except BaseException as e:
         handle_worker_exception(e, outfile)
+        # ensure that the updates to the socket are flushed
+        outfile.flush()
         sys.exit(-1)
     send_accumulator_updates(outfile)