Disable group ack for the consumer (#189)

We actually don't need ack capabilities here at all, so better
to disable the scheduling of the grouped ack flush to avoid any leaks
and useless objects creation.

Cleanup issues should be fixed here
apache/pulsar#5204

plugins/pulsar-records-storage/src/main/java/com/github/bsideup/liiklus/pulsar/PulsarRecordsStorage.java

@@ -22,6 +22,7 @@
 import java.util.concurrent.CompletionStage;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.TimeUnit;
 import java.util.function.Supplier;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
@@ -187,6 +188,7 @@ public Publisher<Record> getPublisher() {
             return Flux.usingWhen(
                     Mono.fromCompletionStage(() -> {
                         val consumerBuilder = pulsarClient.newConsumer()
+                                .acknowledgmentGroupTime(0, TimeUnit.SECONDS) // we don't ack here at all
                                 .subscriptionName(groupName)
                                 .subscriptionType(SubscriptionType.Failover)
                                 .topic(TopicName.get(topic).getPartition(partition).toString());