update built-in chat eval flow

[qusongms]

Description

• update built-in chat eval flow
  • move groundedness to groundedness service
  • add fallback logic when groundedness service is not available in the region
  • change reason column name to _reason
  • add flight control to flow input
• update _metric_handler.py for built-in chat flow
  • add fallback_groundedness_evaluation node to chat node list
  • keep evaluation_per_turn column in output

If an SDK is being regenerated based on a new swagger spec, a link to the pull request containing these swagger spec changes has been included above.

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[github-actions]

Thank you for your contribution @qusongms! We will review the pull request and get back to you soon.

[github-actions]

Hi @qusongms. We've noticed that new changes have been pushed to this pull request. Because it is set to automatically merge, we've reset the approvals to allow the opportunity to review the updates.

Hi @nagkumar91. We've noticed that new changes have been pushed to this pull request. Because it is set to automatically merge, we've reset the approvals to allow the opportunity to review the updates.

[github-actions]

Hi @qusongms. We've noticed that new changes have been pushed to this pull request. Because it is set to automatically merge, we've reset the approvals to allow the opportunity to review the updates.

[github-actions]

Hi @qusongms. We've noticed that new changes have been pushed to this pull request. Because it is set to automatically merge, we've reset the approvals to allow the opportunity to review the updates.

[github-actions]

Hi @qusongms. We've noticed that new changes have been pushed to this pull request. Because it is set to automatically merge, we've reset the approvals to allow the opportunity to review the updates.