Draft: Run @vue/compat on production

What does this MR do and why?

Replaces Vue 2 with @vue/compat on production.

This is just a draft, lots of testing/fixing to do here.

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How to set up and validate locally

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1. Configure a local GitLab Docs environment: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/setup.md.

Merge request acceptance checklist

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