Release pipeline improvement

[hi-ogawa]

• Follow up to chore: setup PR-driven release pipeline #10550

---

• Setup Github App to auto create PR during "prepare publish" workflow dispatch.
  • Currently "prepare publish" job only outputs the compare URL for human to create PR manually. This is because even though auto creating PR from in-repo GITHUB_TOKEN won't trigger the actions on the created PR due to Github's chaining action prevention.
• Automatically derive npm dist-tags for backport release case in publish-ci.ts script.
  • publish-ci.ts currently publishes backport release of npm package as release dist tags. To prevent this, we would need manual fix up for each backport branch like v3 or we should implement automatic way to derive dist-tags.
• Rework changelog and github release generation. For example, changelog generation could be moved ahead to "prepare publish" time.