[fix][broker] Fix BucketDelayedDeliveryTracker thread safety (#24014)

(cherry picked from commit a83dd86)

Author: dao-jun

Diff for: pulsar-broker/src/main/java/org/apache/pulsar/broker/delayed/bucket/BucketDelayedDeliveryTracker.java

@@ -755,7 +755,7 @@ private boolean removeIndexBit(long ledgerId, long entryId) {
                 .orElse(false);
     }
 
-    public boolean containsMessage(long ledgerId, long entryId) {
+    public synchronized boolean containsMessage(long ledgerId, long entryId) {
         if (lastMutableBucket.containsMessage(ledgerId, entryId)) {
             return true;
         }