New sign-in email improvements for OmniAuth sign-ins
The New sign-in email notification is sent for all types of GitLab sign-ins. However, the content is not tailored well for third-party/OmniAuth sign-ins. For example, if I just signed in via Google OAuth, I get an email about the new sign in that suggests I should change my GitLab password if the sign-in wasn't authorized. That advice isn't relevant for sign-ins with OmniAuth.
We could potentially customize the email in case of OmniAuth sign-in, and instead of suggesting the user change their GitLab password, suggest they change their password in Google, enable 2FA in Google, etc.