[minor] Just ignore the Long.MIN_VALUE watermark when creating the ta…

…g. (apache#3490)

paimon-core/src/main/java/org/apache/paimon/tag/TagTimeExtractor.java

@@ -56,7 +56,7 @@ private WatermarkExtractor(ZoneId watermarkZoneId) {
 
         @Override
         public Optional<LocalDateTime> extract(long timeMilli, @Nullable Long watermark) {
-            if (watermark == null || watermark < 0) {
+            if (watermark == null || watermark == Long.MIN_VALUE) {
                 return Optional.empty();
             }