HADOOP-16351. Change ":" to ApplicationConstants.CLASS_PATH_SEPARATOR. Contributed by kevin su.

Signed-off-by: Wei-Chiu Chuang <weichiu@apache.org>

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-applications-distributedshell/src/main/java/org/apache/hadoop/yarn/applications/distributedshell/Client.java

@@ -925,7 +925,7 @@ public class Client {
 
     // add the runtime classpath needed for tests to work
     if (conf.getBoolean(YarnConfiguration.IS_MINI_YARN_CLUSTER, false)) {
-      classPathEnv.append(':')
+      classPathEnv.append(ApplicationConstants.CLASS_PATH_SEPARATOR)
           .append(System.getProperty("java.class.path"));
     }