[SPARK-3677] [BUILD] [YARN] pom.xml and SparkBuild.scala are wrong : Scalastyle is never applied to the sources under yarn/common

When we run "sbt -Pyarn scalastyle" or "mvn package", scalastyle is not applied to the sources under yarn/common.
Hey! So I can build it without your patch. What do you by "we fail to build ?" Can you take that change out from the PR and discuss it separately ?