Submit the post-signup onboarding survey

Deprecated. This path is the pre-/v2/ URL for /v2/users/me/onboarding-survey and is kept only so existing integrations keep working. It behaves identically, responds with a Sunset header, and stops being served on 2027-03-01. Move to /v2/users/me/onboarding-survey.

Persists onboarding survey answers and syncs them to HubSpot