Add test to verify retry of 401s in IMDS client (#1729)

        connection.assert_requests_match(&[]);

    }

    /// 401 error during metadata retrieval must be retried

    #[tokio::test]

    #[traced_test]

    async fn retry_metadata_401() {

        let connection = TestConnection::new(vec![

            (

                token_request("http://169.254.169.254", 21600),

                token_response(0, TOKEN_A),

            ),

            (

                imds_request("http://169.254.169.254/latest/metadata", TOKEN_A),

                http::Response::builder().status(401).body("").unwrap(),

            ),

            (

                token_request("http://169.254.169.254", 21600),

                token_response(21600, TOKEN_B),

            ),

            (

                imds_request("http://169.254.169.254/latest/metadata", TOKEN_B),

                imds_response("ok"),

            ),

        ]);

        let client = make_client(&connection).await;

        assert_eq!(client.get("/latest/metadata").await.expect("success"), "ok");

        connection.assert_requests_match(&[]);

    }

    /// 403 responses from IMDS during token acquisition MUST NOT be retried

    #[tokio::test]

    #[traced_test]