Partials: disable automatic links for custom product pages

[nginx-jack]

Proposed changes

Disables the automatic list of link cards if you add custom content to the root _index.md for a product. There's an exemption here specifically for NGINX One and the solutions page. They should be converted to custom pages down the line, instead of their current setup.

I aim to remove these list and list-main partials entirely from this repository, and instead, provide the right set of partials/shortcodes/templates directly from the theme.

Should not be merged until nginxinc/nginx-hugo-theme#210 is released

Closes #ISSUE

Checklist

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• I have read the contributing guidelines
• I have signed the F5 Contributor License Agreement (CLA)
• I have rebased my branch onto main
• I have ensured my PR is targeting the main branch and pulling from my branch from my own fork
• I have ensured that the commit messages adhere to Conventional Commits
• I have ensured that documentation content adheres to the style guide
• If the change involves potentially sensitive changes¹, I have assessed the possible impact
• If applicable, I have added tests that prove my fix is effective or that my feature works
• I have ensured that existing tests pass after adding my changes
• If applicable, I have updated README.md and CHANGELOG.md

Footnotes

1. Potentially sensitive changes include anything involving code, personally identify information (PII), live URLs or significant amounts of new or revised documentation. Please refer to our style guide for guidance about placeholder content. ↩

[github-actions]

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[nginx-jack]

Needs some tweaks - Some empty products aren't rendering lists properly. Will update.

[nginx-jack]

Needs some tweaks - Some empty products aren't rendering lists properly. Will update.

Ready for review 👍