Migrate intra-article app links to legacy. #2804
Description
We've now launched the exact same App v1 on the legacy. prefix alongside the default domain. To prevent breakage, we need to migrate the App v1 links inside the articles to the legacy. domain, such that even when using App v1 on the default domain, you're directed to the legacy-domained app. This is part of the migration plan to putting App v2 on the default domain.