Draft: Add soft warning to VISA users about service impact

What does this MR do and why?

This is just a draft / idea expressed in code.

Add a link to the checkout to give notice to users to be aware of potential issues.

Meant to aid in lessening the impact of https://gitlab.com/gitlab-com/gl-infra/production/-/issues/6709.

Screenshots or screen recordings

MR acceptance checklist

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