Fix prefect config view not showing .env file settings

[GalLadislav]

This PR fixes prefect config view for .env file settings with added tests.

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
• If this pull request removes docs files, it includes redirect settings in mint.json.
• If this pull request adds functions or classes, it includes helpful docstrings.

[codspeed-hq]

CodSpeed Performance Report

Merging #15922 will not alter performance

_{Comparing GalLadislav:fix-cli-config-view-for-dotenv (fabba7a) with main (190c994)}

Summary

✅ 3 untouched benchmarks

[desertaxle]

Thank you!