🐛 Bug: remove or replace `eslint-plugin-markdown`

[michaelfaith]

Bug Report Checklist

• I have tried restarting my IDE and the issue persists.
• I have pulled the latest main branch of the repository.
• I have searched for related issues and found none that matched my issue.

CTA is currently generating eslint configs that use eslint-plugin-markdown, which was deprecated last year in favor of @eslint/markdown. But the project is also set up with markdownlint. Considering there's this blocked issue for moving from markdownlint to @eslint/markdown (#1926), I would recommend removing the deprecated eslint-plugin-markdown entirely. Not only does it serve as a second "source of truth" but is effectively competing with markdownlint in its current form.