[HUDI-3043] Revert async cleaner leak commit to unblock CI failure (#4343)

* Revert "[HUDI-2959] Fix the thread leak of cleaning service (#4252)"
Reverting to unblock CI failure for now. will revisit this with the right fix

hudi-flink/src/main/java/org/apache/hudi/sink/CleanFunction.java

@@ -98,11 +98,4 @@ public class CleanFunction<T> extends AbstractRichFunction
   public void initializeState(FunctionInitializationContext context) throws Exception {
     // no operation
   }
-
-  @Override
-  public void close() throws Exception {
-    if (this.writeClient != null) {
-      this.writeClient.close();
-    }
-  }
 }