keystore: Change the dummy HsClientSpecifier to "default".

                let netdir = self.netdir(Timeliness::Timely, "connect to a hidden service")?;

                // TODO hs: use a real client id (loaded from the config)

                let client_id = HsClientSpecifier::new("not_a_real_spec".into())

                let client_id = HsClientSpecifier::new("default".into())

                    .map_err(|e| ErrorDetail::Keystore(e))?;

                let desc_enc_key_spec = HsClientSecretKeySpecifier::new(

                    client_id.clone(),