[Improve][Checkpoint] Use fixed serialVersionUID in sink state class (#9079)

Author: hailin0

Diff for: seatunnel-api/src/main/java/org/apache/seatunnel/api/sink/multitablesink/SinkIdentifier.java

@@ -25,6 +25,8 @@
 @Getter
 @EqualsAndHashCode
 public class SinkIdentifier implements Serializable {
+    // Use jvm default serial version uid
+    private static final long serialVersionUID = 5378869132870084393L;
 
     private final String tableIdentifier;