Revert "Expose OpenVINO batch_size similarly to TensorRT" (#8510)

Revert "Expose OpenVINO `batch_size` similarly to TensorRT (#8437)"

This reverts commit da2ee3934e.

models/common.py

@@ -366,7 +366,6 @@ class DetectMultiBackend(nn.Module):
             if not Path(w).is_file():  # if not *.xml
                 w = next(Path(w).glob('*.xml'))  # get *.xml file from *_openvino_model dir
             network = ie.read_model(model=w, weights=Path(w).with_suffix('.bin'))
-            batch_size = network.batch_size
             executable_network = ie.compile_model(network, device_name="CPU")  # device_name="MYRIAD" for Intel NCS2
             output_layer = next(iter(executable_network.outputs))
             meta = Path(w).with_suffix('.yaml')