Compare raw values when merging expiration in WAN [HZ-3661] [5.3.6] (#…

…25932)

Backport of #25899

Comparing non-raw values invokes deserialization on the target member,
which should not occur, and a raw value comparison is sufficient for our
checks here. I've run QE's WAN ITs locally, including newly added TTL
tests for the original issue, to verify functionality is not affected.

Related to #25627
Fixes https://hazelcast.atlassian.net/browse/HZ-3661

hazelcast/src/main/java/com/hazelcast/map/impl/recordstore/DefaultRecordStore.java

@@ -1124,7 +1124,7 @@ public boolean merge(MapMergeTypes<Object, Object> mergingEntry,
                 //  changed data and use that. Since this only matters for WAN-received merge events, we can avoid
                 //  additional overhead by checking provenance. Fixes HZ-3392, Backlog for merge changes: HZ-3397
                 boolean shouldMergeExpiration = provenance != CallerProvenance.WAN
-                        || valueComparator.isEqual(oldValue, mergingEntry.getValue(), serializationService);
+                        || valueComparator.isEqual(existingEntry.getRawValue(), mergingEntry.getRawValue(), serializationService);
                 if (shouldMergeExpiration) {
                     mergeRecordExpiration(key, record, mergingEntry, now);
                 }