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

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 <[email protected]>

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

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

Author: sarutak

dev/scalastyle

@@ -26,6 +26,8 @@ echo -e "q\n" | sbt/sbt -Pyarn -Phadoop-2.2 -Dhadoop.version=2.2.0 yarn/scalasty
   >> scalastyle.txt
 
 ERRORS=$(cat scalastyle.txt | grep -e "\<error\>")
+rm scalastyle.txt
+
 if test ! -z "$ERRORS"; then
     echo -e "Scalastyle checks failed at following occurrences:\n$ERRORS"
     exit 1