Checkstyle fix

Author: ash211

core/src/test/java/org/apache/spark/launcher/SparkLauncherSuite.java

@@ -21,7 +21,6 @@
 import java.util.HashMap;
 import java.util.Map;
 
-import org.junit.Before;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

launcher/src/test/java/org/apache/spark/launcher/ChildProcAppHandleSuite.java

@@ -18,7 +18,6 @@
 package org.apache.spark.launcher;
 
 import java.io.File;
-import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;