Refactor lazy imports to avoid accidental eager imports

[abrookins]

This work is part of our effort to speed up CLI commands. The lazy_import function inadvertently imported more things when you called it, particularly a bunch of Docker and Kubernetes packages. The problem was the function's call to inspect.stack(), which was only necessary to produce a detailed error message. I tightened the error message to remove the need to call inspect.stack().

Example

Checklist

• This pull request references any related issue by including "closes <link to issue>"
  • If no issue exists and your change is not a small fix, please create an issue first.
• If this pull request adds new functionality, it includes unit tests that cover the changes
• This pull request includes a label categorizing the change e.g. maintenance, fix, feature, enhancement, docs.

For documentation changes:

• This pull request includes redirect settings in netlify.toml for files that are removed or renamed.

For new functions or classes in the Python SDK:

• This pull request includes helpful docstrings.
• If a new Python file was added, this pull request contains a stub page in the Python SDK docs and an entry in mkdocs.yml navigation.

[netlify]

✅ Deploy Preview for prefect-docs-preview ready!

Name	Link
🔨 Latest commit	78e8a79
🔍 Latest deploy log	https://app.netlify.com/sites/prefect-docs-preview/deploys/664368afbb6fde0008318711
😎 Deploy Preview	https://deploy-preview-13296--prefect-docs-preview.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[abrookins]

Tests are currently failing due to an upstream change in the apprise library that we're working to fix.

[chrisguidry]

Super interesting, what mechanism caused the additional imports to happen?

[abrookins]

@chrisguidry I haven't had time to dig into this yet, but it was inspect.stack()[1].

[abrookins]

The problem was that using inspect would evaluate imports at the frame above the current frame, which would end up eagerly importing kubernetes.