[Debt] Unused partials and layouts should be removed

### Current Behavior
Some partials and templates like [this](https://github.com/layer5io/docs/blob/929a84e14840010fee135c1135f10396ecb9de8f/layouts/partials/plan-info.html) exist, but aren't used anywhere

### Expected Behavior
Identifying and removing them would clean up the codebase.

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#### Contributor Guide and Resources
- 📚 [Instructions for contributing to documentation](https://github.com/layer5io/docs/blob/master/CONTRIBUTING.md)
- Layer5 documentation [site](https://docs.layer5.io) and [source](https://github.com/layer5io/docs/)
- 🎨 Wireframes and [designs for Layer5 site](https://www.figma.com/file/5ZwEkSJwUPitURD59YHMEN/Layer5-Designs) in Figma [(open invite)](https://www.figma.com/team_invite/redeem/GvB8SudhEOoq3JOvoLaoMs)
- 🙋🏾🙋🏼 Questions: [Layer5 Discussion Forum](https://discuss.layer5.io) and [Layer5 Community Slack](http://slack.layer5.io)

Start with layouts/partials/plan-info.html and inspect the layouts and templates for references to it and other unused partials. Identify candidates that have no usage, verify they are not required by the documentation site, and consider the work done when confirmed-unused files are removed without affecting the site.

Written by the indexing model from the issue text.