[Fix][Connector-V2] Fix CSV String type write type

[corgy-w]

Purpose of this pull request

Fix CSV String type write type

Does this PR introduce any user-facing change?

How was this patch tested?

UT

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.

[corgy-w]

@Hisoka-X ci has passed, accidentally merge dev, please review it

[Hisoka-X]

Please fix test case.

[corgy-w]

Please fix test case.

#8448

[corgy-w]

@Hisoka-X please review it