Remove useless code to reduce confusion

[poorbarcode]

Describe the bug

pulsar/pulsar-client/src/main/java/org/apache/pulsar/client/impl/PersistentAcknowledgmentsGroupingTracker.java

Lines 325 to 355 in 46baae6

	private CompletableFuture<Void> doCumulativeAck(MessageIdImpl messageId, Map<String, Long> properties,
	BitSetRecyclable bitSet) {
	consumer.getStats().incrementNumAcksSent(consumer.getUnAckedMessageTracker().removeMessagesTill(messageId));
	if (acknowledgementGroupTimeMicros == 0 || (properties != null && !properties.isEmpty())) {
	// We cannot group acks if the delay is 0 or when there are properties attached to it. Fortunately that's an
	// uncommon condition since it's only used for the compaction subscription.
	return doImmediateAck(messageId, AckType.Cumulative, properties, bitSet);
	} else {
	if (isAckReceiptEnabled(consumer.getClientCnx())) {
	// when flush the ack, we should bind the this ack in the currentFuture, during this time we can't
	// change currentFuture. but we can lock by the read lock, because the currentFuture is not change
	// any ack operation is allowed.
	this.lock.readLock().lock();
	try {
	doCumulativeAckAsync(messageId, bitSet);
	return this.currentCumulativeAckFuture;
	} finally {
	this.lock.readLock().unlock();
	if (pendingIndividualBatchIndexAcks.size() >= MAX_ACK_GROUP_SIZE) {
	flush();
	}
	}
	} else {
	doCumulativeAckAsync(messageId, bitSet);
	if (pendingIndividualBatchIndexAcks.size() >= MAX_ACK_GROUP_SIZE) {
	flush();
	}
	return CompletableFuture.completedFuture(null);
	}
	}
	}

L343 - L345 & L349-L351
It looks like unnecessary

this method doCumulativeAckAsync(messageId, bitSet) only update variable lastCumulativeAck, will not change pendingIndividualBatchIndexAcks

[github-actions]

The issue had no activity for 30 days, mark with Stale label.

[github-actions]

The issue had no activity for 30 days, mark with Stale label.

[poorbarcode]

It has been fixed at #15877, so close this pull request.