We were previously storing the primaryIdentityPublicKey in the public_key column of the cookies table. We're going to strip this logic out before DB migration that removes the public_key column altogether.

Will remove from siweAuthResponder next (and all the helper functions involved).

1. Login ("traditional")
2. Set breakpoints and observe that public_key column of cookies table isn't being set.
3. Check cookies table make sure that most recent entry lacks public_key.