[Improve][Transform] Update MetadataTransformConfig extends

[hailin0]

Purpose of this pull request

[Transform] Update MetadataTransformConfig extends

Does this PR introduce any user-facing change?

No

How was this patch tested?

Check list

• If any new Jar binary package adding in your PR, please add License Notice according
  New License Guide
• If necessary, please update the documentation to describe the new feature. https://github.com/apache/seatunnel/tree/dev/docs
• If you are contributing the connector code, please check that the following files are updated:
  1. Update plugin-mapping.properties and add new connector information in it
  2. Update the pom file of seatunnel-dist
  3. Add ci label in label-scope-conf
  4. Add e2e testcase in seatunnel-e2e
  5. Update connector plugin_config
• Update the release-note.

[Copilot]

Pull Request Overview

This PR updates the inheritance of MetadataTransformConfig by removing its dependency on ModelTransformConfig and instead implements Serializable.

• Removed the extension of ModelTransformConfig.
• Updated imports to reflect the change in class inheritance.

Comments suppressed due to low confidence (1)

seatunnel-transforms-v2/src/main/java/org/apache/seatunnel/transform/metadata/MetadataTransformConfig.java:26

• Removing the extension from ModelTransformConfig might remove inherited functionality or configuration defaults relied upon elsewhere; please confirm that this change is intentional and that all necessary behavior is preserved.

public class MetadataTransformConfig implements Serializable {