Fix the issue that download retry may timeout without retry (#1137)

The reason is that the `Retry` operation include the elapsed time of
the first attempt into the total elapsed time, if the network is slow
and the first attempt consume too much time, the `Retry` operation
will timeout.

Fix #1015

Co-authored-by: Ti Chi Robot <71242396+ti-chi-bot@users.noreply.github.com>

pkg/repository/mirror.go

@@ -493,6 +493,9 @@ func (l *httpMirror) Download(resource, targetDir string) error {
 			return nil
 		}
 		return r.Close()
+	}, utils.RetryOption{
+		Timeout:  time.Hour,
+		Attempts: 3,
 	})
 	if err != nil {
 		return err