[SPARK-2904] Remove non-used local variable in SparkSubmitArguments

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

Closes #1834 from sarutak/SPARK-2904 and squashes the following commits:

38e7d45 [Kousuke Saruta] Removed non-used variable in SparkSubmitArguments
(cherry picked from commit 9de6a42bb34ea8963225ce90f1a45adcfee38b58)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>