ZOOKEEPER-4807: Add sid in the leader goodbyte log.

Reviewers: maoling
Author: horizonzy
Closes #2131 from horizonzy/tune-leader-goodbye-follower-log

zookeeper-server/src/main/java/org/apache/zookeeper/server/quorum/LearnerHandler.java

@@ -733,7 +733,7 @@ public class LearnerHandler extends ZooKeeperThread {
                 syncThrottler = null;
             }
             String remoteAddr = getRemoteAddress();
-            LOG.warn("******* GOODBYE {} ********", remoteAddr);
+            LOG.warn("******* GOODBYE sid:{} {} ********", getSid(), remoteAddr);
             messageTracker.dumpToLog(remoteAddr);
             shutdown();
         }