HDFS-16235. Fix Deadlock in LeaseRenewer for static remove method (#3472)

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/impl/LeaseRenewer.java

@@ -96,7 +96,9 @@ public class LeaseRenewer {
    * @param renewer Instance to be cleared from Factory
    */
   public static void remove(LeaseRenewer renewer) {
-    Factory.INSTANCE.remove(renewer);
+    synchronized (renewer) {
+      Factory.INSTANCE.remove(renewer);
+    }
   }
 
   /**