HADOOP-19433. Improve Some Code.

Author: slfan1989

hadoop-tools/hadoop-extras/src/test/java/org/apache/hadoop/mapred/tools/TestGetGroups.java

@@ -55,36 +55,30 @@ protected Tool getTool(PrintStream o) {
   @Test
   @Override
   public void testNoUserGiven() throws Exception {
-    super.testNoUserGiven();
   }
 
   @Test
   @Override
   public void testExistingUser() throws Exception {
-    super.testExistingUser();
   }
 
   @Test
   @Override
   public void testMultipleExistingUsers() throws Exception {
-    super.testMultipleExistingUsers();
   }
 
   @Test
   @Override
   public void testNonExistentUser() throws Exception {
-    super.testNonExistentUser();
   }
 
   @Test
   @Override
   public void testMultipleNonExistingUsers() throws Exception {
-    super.testMultipleNonExistingUsers();
   }
 
   @Test
   @Override
   public void testExistingInterleavedWithNonExistentUsers() throws Exception {
-    super.testExistingInterleavedWithNonExistentUsers();
   }
 }