Update favicons

What does this MR do and why?

• Updates favicons to adhere to updated branding guidelines with the new logo.
• Removes Microsoft Tile icon and config; this is no longer needed for MS Edge (https://evilmartians.com/chronicles/how-to-favicon-in-2021-six-files-that-fit-most-needs).

Closes #1252 (closed)

Screenshots, screen recordings, or links to review app

Chrome	Safari	MS Edge	Apple touch icon

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.
2. View the site favicon in your browser tabs and bookmarks

Or check it out here: http://sarahg-1252-favicon.35.193.151.162.nip.io/

Merge request acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this merge request.