fix(spark): clean up SparkConnect CR on failure and align states

[TensorDevLJ]

Fixes #476

Summary

• Best-effort delete SparkConnect CR when wait/connect fails after create
• Align SparkConnectState with Spark Operator (add New, remove Running)
• Add unit tests for cleanup failure paths

Notes

State alignment overlaps with #572 / #577; this PR also covers the cleanup gap from #476.

Test plan

• backend create_and_connect cleanup tests
• SparkConnectState / utils parse tests
• ruff check/format on touched files

[google-oss-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
Once this PR has been reviewed and has the lgtm label, please assign andreyvelich for approval. For more information see the Kubernetes Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[github-actions]

🎉 Welcome to the Kubeflow SDK! 🎉

Thanks for opening your first PR! We're happy to have you as part of our community 🚀

Here's what happens next:

• If you haven't already, please check out our Contributing Guide for repo-specific guidelines and the Kubeflow Contributor Guide for general community standards
• Our team will review your PR soon! cc @kubeflow/kubeflow-sdk-team

Join the community:

• Slack: Join our #kubeflow-ml-experience and #kubeflow-trainer Slack channels
• Meetings: Attend the Kubeflow SDK and ML Experience bi-weekly meetings

Feel free to ask questions in the comments if you need any help or clarification!
Thanks again for contributing to Kubeflow! 🙏