remove stale sleep code in BookieServer (#4336)

Signed-off-by: ZhangJian He <shoothzj@gmail.com>
diff --git a/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieServer.java b/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieServer.java
index 049425a..da2cbd8 100644
--- a/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieServer.java
+++ b/bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieServer.java
@@ -29,7 +29,6 @@
 import java.lang.Thread.UncaughtExceptionHandler;
 import java.net.UnknownHostException;
 import java.util.Arrays;
-import java.util.concurrent.TimeUnit;
 import org.apache.bookkeeper.bookie.Bookie;
 import org.apache.bookkeeper.bookie.BookieCriticalThread;
 import org.apache.bookkeeper.bookie.BookieException;
@@ -150,10 +149,6 @@
             deathWatcher.setUncaughtExceptionHandler(uncaughtExceptionHandler);
         }
         deathWatcher.start();
-
-        // fixes test flappers at random places until ISSUE#1400 is resolved
-        // https://github.com/apache/bookkeeper/issues/1400
-        TimeUnit.MILLISECONDS.sleep(250);
     }
 
     @VisibleForTesting