[SPARK-3192] Some scripts have 2 space indentation but other scripts have 4 space indentation.

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #2104 from sarutak/SPARK-3192 and squashes the following commits:

db78419 [Kousuke Saruta] Modified indentation of spark-shell