Remove loer, precision, map_cer_per_class, layout_precision_per_class_per_threshold

We should remove loer, precision, map_cer_per_class, layout_precision_per_class_per_threshold metrics and all occurences as they are not used. See https://gitlab.com/teklia/atr/dan/-/blob/66f0f92db68d23c1312c617c8556169b5423e18c/dan/manager/metrics.py#L35