[lib] Discard keyserver usernames for keyserverAuthActionTypes

Summary:
issue: ENG-8365
update_relationships throws for viewers own id, because it doesn't make sense to be updating users relationship with themselves. But the user should always have their own user info sent during keyserver auth, so there is no need to fetch it, for any action

Test Plan: Logged in. Checked that usernames for both the current user and other users are null after keyserver auth and get fetched from identity. Checked that the invalid_user error doesn't show up.

Reviewers: tomek, kamil

Reviewed By: kamil

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D12509