Cleanup Detector labelmap (#4932)

* Add missing labels to default labelmap.  Fill any holes with "unknown".  Remove unique labelmap for tensorrt.

* Replace "truck" with "car" on Openvino labelmap

docker/tensorrt_models.sh

@@ -32,6 +32,3 @@ do
     python3 onnx_to_tensorrt.py -m ${model}
     cp /tensorrt_demos/yolo/${model}.trt ${OUTPUT_FOLDER}/${model}.trt;
 done
-
-# Download Labelmap
-wget -q https://github.com/openvinotoolkit/open_model_zoo/raw/master/data/dataset_classes/coco_91cl.txt -O ${OUTPUT_FOLDER}/coco_91cl.txt