[SPARK-3547]Using a special exit code instead of 1 to represent ClassNotFoundExcepti...

...on

As improvement of https://github.com/apache/spark/pull/1944, we should use more special exit code to represent ClassNotFoundException.
Please keep error codes < 128. From http://en.wikipedia.org/wiki/Exit_status:

    When a command terminates on a fatal signal whose number is N, Bash uses the value 128+N as the exit status.