[fix][broker] fix getMaxReadPosition in TransactionBufferDisable should return latest (#24898)

Co-authored-by: fanjianye <fanjianye@bigo.sg>

Author: TakaHiR07

pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/PersistentTopic.java

@@ -4140,6 +4140,12 @@ public CompletableFuture<Position> getLastDispatchablePosition() {
         if (lastDispatchablePosition != null) {
             return CompletableFuture.completedFuture(lastDispatchablePosition);
         }
+        Position lastPosition;
+        if (transactionBuffer instanceof TransactionBufferDisable) {
+            lastPosition = getLastPosition();
+        } else {
+            lastPosition = getMaxReadPosition();
+        }
         return ledger.getLastDispatchablePosition(entry -> {
             MessageMetadata md = entry.getMessageMetadata();
             if (md == null) {
@@ -4154,7 +4160,7 @@ public CompletableFuture<Position> getLastDispatchablePosition() {
                 return !isTxnAborted(txnID, entry.getPosition());
             }
             return true;
-        }, getMaxReadPosition()).thenApply(position -> {
+        }, lastPosition).thenApply(position -> {
             // Update lastDispatchablePosition to the given position
             updateLastDispatchablePosition(position);
             return position;

pulsar-broker/src/main/java/org/apache/pulsar/broker/transaction/buffer/impl/TransactionBufferDisable.java

@@ -23,6 +23,7 @@
 import java.util.concurrent.CompletableFuture;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.bookkeeper.mledger.Position;
+import org.apache.bookkeeper.mledger.PositionFactory;
 import org.apache.pulsar.broker.service.BrokerServiceException;
 import org.apache.pulsar.broker.service.Topic;
 import org.apache.pulsar.broker.service.persistent.PersistentTopic;
@@ -108,7 +109,7 @@ public void syncMaxReadPositionForNormalPublish(Position position, boolean isMar
 
     @Override
     public Position getMaxReadPosition() {
-        return topic.getLastPosition();
+        return PositionFactory.LATEST;
     }
 
     @Override