ci: add Cloudberry docker-based build+installcheck gate

[Mulily0513]

• Add GitHub Actions workflow to run PL/Java build/test against Cloudberry
• Provide reproducible ubuntu22.04 docker-compose environment
• Build/install Cloudberry demo cluster inside container
• Build/install PL/Java and run built-in regression (make installcheck)
• Update expected output for Cloudberry-specific differences

fix #ISSUE_Number

---

Change logs

Describe your change clearly, including what problem is being solved or what document is being added or updated.

Contributor's checklist

Here are some reminders before you submit your pull request:

• Make sure that your Pull Request has a clear title and commit message. You can take the Git commit template as a reference.
• Sign the Contributor License Agreement as prompted for your first-time contribution (One-time setup).
• Learn the code contribution and doc contribution guides for better collaboration.
• List your communications in the GitHub Issues or Discussions (if has or needed).
• Feel free to ask for the cloudberrydb team to help review and approve.