## What changes were proposed in this pull request?

Adding the default UncaughtExceptionHandler to the Worker.

## How was this patch tested?

I verified it manually, when any of the worker thread gets uncaught exceptions then the default UncaughtExceptionHandler will handle those exceptions.

Author: Devaraj K <devaraj@apache.org>

Closes #18357 from devaraj-kavali/SPARK-21146.