Finish user onboarding for existing enterprise users

What does this MR do and why?

Finish user onboarding when the user is an enterprise user

• backfilling existing users
• future cases being handled in !182649 (merged)
  • !184478 (merged) to cleanup the feature flag has made it to production, so we can now schedule the backfill
• see #520498 (closed)

Changelog: other

MR acceptance checklist

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Related to #520498 (closed)