dev/scalastyle create a log file 'scalastyle.txt'. it is overwrote per running but never deleted even though dev/mima and dev/lint-python delete their log files.

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

Closes #2702 from sarutak/scalastyle-txt-cleanup and squashes the following commits:

d6e238e [Kousuke Saruta] Fixed dev/scalastyle to cleanup scalastyle.txt