SPARK-3480 - Throws out Not a valid command 'yarn-alpha/scalastyle' in dev/scalastyle for sbt build tool during 'Running Scala style checks'

Symptom:
Run ./dev/run-tests and dump outputs as following:
....
Running Scala style checks
Scalastyle checks failed at following occurrences:
[error] Expected ID character
[error] Not a valid command: yarn-alpha
[error] Expected project ID
[error] Expected configuration
[error] Expected ':' (if selecting a configuration)
[error] Expected key
[error] Not a valid key: yarn-alpha
[error] yarn-alpha/scalastyle
[error] ^

Possible Cause:
I checked the dev/scalastyle, found that there are 2 parameters 'yarn-alpha/scalastyle' and 'yarn/scalastyle' separately,like
echo -e "q\n" | sbt/sbt -Pyarn -Phadoop-0.23 -Dhadoop.version=0.23.9 yarn-alpha/scalastyle \
>> scalastyle.txt

echo -e "q\n" | sbt/sbt -Pyarn -Phadoop-2.2 -Dhadoop.version=2.2.0 yarn/scalastyle \
>> scalastyle.txt

From above error message, sbt seems to complain them due to '/' separator. So it can be run through after I manually modified original ones to 'yarn-alpha:scalastyle' and 'yarn:scalastyle'..