MAPREDUCE-6370. Made the timeline service v2 test driver write event ID. Contributed by Li Lu.

(cherry picked from commit 827633ee9fee26e3e15343cbccb0b7905ae02170)

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-jobclient/src/test/java/org/apache/hadoop/mapred/SimpleEntityWriter.java

@@ -97,6 +97,7 @@ class SimpleEntityWriter extends EntityWriter {
         entity.addInfo("PERF_TEST", payLoad);
         // add an event
         TimelineEvent event = new TimelineEvent();
+        event.setId("foo_event_id");
         event.setTimestamp(System.currentTimeMillis());
         event.addInfo("foo_event", "test");
         entity.addEvent(event);