YARN-7153. Remove duplicated code in AMRMClientAsyncImpl.java. Contributed by Sen Zhao.

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-client/src/main/java/org/apache/hadoop/yarn/client/api/async/impl/AMRMClientAsyncImpl.java

@@ -142,11 +142,7 @@ extends AMRMClientAsync<T> {
     handlerThread.interrupt();
     super.serviceStop();
   }
-  
-  public void setHeartbeatInterval(int interval) {
-    heartbeatIntervalMs.set(interval);
-  }
-  
+
   public List<? extends Collection<T>> getMatchingRequests(
                                                    Priority priority, 
                                                    String resourceName,