remove future.join() from PulsarSinkEffectivelyOnceProcessor (#6361)

(cherry picked from commit 943c903)

Author: nlu90

pulsar-functions/instance/src/main/java/org/apache/pulsar/functions/sink/PulsarSink.java

@@ -234,7 +234,6 @@ public void sendOutputMessage(TypedMessageBuilder<T> msg, Record<T> record) {
             CompletableFuture<MessageId> future = msg.sendAsync();
 
             future.thenAccept(messageId -> record.ack()).exceptionally(getPublishErrorHandler(record, true));
-            future.join();
         }
     }