[SPARK-3843][Minor] Cleanup scalastyle.txt at the end of running dev/scalastyle

[sarutak]

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.

[SparkQA]

QA tests have started for PR 2702 at commit d6e238e.

• This patch merges cleanly.

[SparkQA]

QA tests have finished for PR 2702 at commit d6e238e.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test FAILed.
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Test FAILed.
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[sarutak]

retest this please.

[SparkQA]

QA tests have started for PR 2702 at commit d6e238e.

• This patch merges cleanly.

[SparkQA]

QA tests have finished for PR 2702 at commit d6e238e.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test PASSed.
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[pwendell]

Yeah - good idea. I can merge this.