Make Authenticate less misleading

Because clients clone in the API now, setting the token on the
authtokens client may mislead the user into thinking it's setting it on
the base client. Remove that set call.

api/authmethods/authenticate.go

@@ -35,9 +35,5 @@ func (c *Client) Authenticate(ctx context.Context, authMethodId string, credenti
 		return nil, nil, fmt.Errorf("error decoding Authenticate response: %w", err)
 	}
 
-	if target.Token != "" {
-		c.client.SetToken(target.Token)
-	}
-
 	return target, apiErr, nil
 }