MVC 1 - Platform page table update

Step 1: What is changing in this MR?

This MR renames the stages used on the /platform page.

It also swaps the priority of what is linked to for each features, with marketing_page taking priority of feature_page when present in categories.yml

Production	Review app
https://about.gitlab.com/platform/	https://3701-platform-page-update-table.about.gitlab-review.app/platform/
https://about.gitlab.com/features/	https://3701-platform-page-update-table.about.gitlab-review.app/features/

Step 2: Ensure that your changes comply with the following, where applicable:

• I, the Assignee, have run Axe tools on any updated pages, and fixed the relevant accessibility issues.
• These changes work on both Safari, Chrome, and Firefox.
• These changes have been reviewed for Visual Quality Assurance and Functional Quality Assurance on Mobile, Desktop, and Tablet.
• These changes work with our Google Analytics and SEO tools.
• These changes have been documented as expected.

Build Variables:

• Use Contentful Preview API

Related #3701 (closed)