[fix][broker] Fix memory leak during topic compaction (apache#21647)

(cherry picked from commit d5457d3)

pulsar-broker/src/main/java/org/apache/pulsar/compaction/TwoPhaseCompactor.java

@@ -256,6 +256,7 @@ private void phaseTwoLoop(RawReader reader, MessageId to, Map<String, MessageId>
             }
 
             if (m.getMessageId().compareTo(lastCompactedMessageId) <= 0) {
+                m.close();
                 phaseTwoLoop(reader, to, latestForKey, lh, outstanding, promise, lastCompactedMessageId);
                 return;
             }