HDFS-11135. The tests in TestBalancer run fails due to NPE. Contributed By Yiqun Lin

(cherry picked from commit 6efb8c9c6018ec688eeba8c61c220009ec350a44)

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java

@@ -252,9 +252,9 @@ public class TestBalancer {
   public static void destroy() throws Exception {
     if (kdc != null) {
       kdc.stop();
-    }
-    FileUtil.fullyDelete(baseDir);
+      FileUtil.fullyDelete(baseDir);
       KeyStoreTestUtil.cleanupSSLConfig(keystoresDir, sslConfDir);
+    }
   }
 
   /* create a file with a length of <code>fileLen</code> */