OIDC plugin credential validator failed

[Cantor, Scott]

> Hm, seems Credential Validator oauth2-... logs at INFO, not
> ERROR.

Failed authentication isn't an error because it's routine when operating an IdP and generally isn't anything the IdP operator can address, but is on INFO so it's at least visible when asked about it.

We probably don't have audit logging wired into the OAuth flow now that I think about it, not sure, that was somewhat recently added to the IdP's login flows as a capability. That should probably be fixed.

-- Scott