[client] Downgrade PartitionNotExistException log level from WARN to DEBUG (#3019)

Author: YannByron

fluss-client/src/main/java/org/apache/fluss/client/metadata/MetadataUpdater.java

@@ -285,7 +285,7 @@ public void updateMetadata(
                 }
                 LOG.warn("Failed to update metadata, but the exception is re-triable.", t);
             } else if (t instanceof PartitionNotExistException) {
-                LOG.warn("Failed to update metadata because the partition does not exist", t);
+                LOG.debug("Failed to update metadata because the partition does not exist", t);
                 throw (PartitionNotExistException) t;
             } else {
                 throw new FlussRuntimeException("Failed to update metadata", t);