Clear User.studio_person_id as part of user purge.

[ashercodeorg]

No description provided.

[ashercodeorg]

@poorvasingal: Do we want to clear the StudioPerson profile when any associated account is purged? When the last associated account is purged? Never?

[poorvasingal]

We would probably clear StudioPerson when the last account is deleted. And if multiple accounts are associated with StudioPerson, then just make sure we disassociate the purged account with the StudioPerson.

[ashercodeorg]

Talking with @bencodeorg, I'm going to leave clearing the StudioPerson (if now isolated) to follow-up work since we don't yet know how the model structure will be changing (though we expect some imminent changes).