[SPARK-3399][PySpark] Test for PySpark should ignore HADOOP_CONF_DIR and YARN_CONF_DIR

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

Closes #2270 from sarutak/SPARK-3399 and squashes the following commits:

7613be6 [Kousuke Saruta] Modified pyspark script to ignore environment variables YARN_CONF_DIR and HADOOP_CONF_DIR while testing