Allow Setting `original_config_file` for Diffusers Backend

[thiner]

Is your feature request related to a problem? Please describe.

I encountered an error while using diffusers backend for text-to-image service. Loading model failed due to error:
ERR Server error error="could not load model (no success): Unexpected err=OSError('DreamShaperXL_Turbo_v2_1.safetensors does not appear to have a file named model_index.json.'), type(err)=<class 'OSError'>".
According to the discussion huggingface/diffusers#7209 (comment) from_single_file function need the argument original_config_file in a offline environment.

Describe the solution you'd like

Please improve backend/python/diffusers/backend.py, allow pass in original_config_file while loading model from local.

Describe alternatives you've considered

n/a

Additional context

huggingface/diffusers#7209