Unindex cookie policies page from Google

Create a new layout (or just tweak the current) to get https://docs.gitlab.com/cookies-policy/ out of Google search. (noindex nofollow)

Reasons:

• We eventually need to prevent Google from indexing pages, so I created the logic to do this out-of-the-box from the page's frontmatter
• The cookies page, from what I understood, is some magic way to display the cookies consent, therefore, we don't need it popping up in Google searches.