* sort by confidence and remove excess boxes without explicit if
Signed-off-by: Yonghye Kwon <developer.0hye@gmail.com>

* cleanup indexing boxes for remove excess boxes

it is related to https://github.com/ultralytics/yolov5/pull/10502.
Signed-off-by: Yonghye Kwon <developer.0hye@gmail.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>