[Improve][Zeta] Make the default value of classloader-cache-mode is true

[dailai]

Purpose of this pull request

Does this PR introduce any user-facing change?

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.

[Hisoka-X]

Please update the doc.

[dailai]

Please update the doc.

done

[Hisoka-X]

Setting this configuration true or false will bring different problems, but generally, setting this configuration true is more user-friendly for most users, and it makes the server more stable.

[Hisoka-X]

This change break our thread leak check. We should revert it first.

[Hisoka-X]

This change break our thread leak check. We should revert it first.

#7940