model-conversion : pass config to from_pretrained (#16963)

model-conversion : pass config to from_pretrained (#16963)

This commit modifies the script `run-org-model.py` to ensure that the
model configuration is explicitly passed to the `from_pretrained` method
when loading the model. It also removes a duplicate configuration
loading which was a mistake.

The motivation for this change is that enables the config object to be
modified and then passed to the model loading function, which can be
useful when testing new models.