[fix] Fix loading pre-exported OV/ONNX model if export=False

[tomaarsen]

Hello!

Pull Request overview

• Fix loading pre-exported OV/ONNX model if export=False

Details

If export=False, then the subfolder and file_name are not set based on the current situation. This results in the model not being found. For example:

from sentence_transformers import SentenceTransformer

# Works!
model = SentenceTransformer("all-MiniLM-L6-v2", backend="onnx")
# Failed!
model = SentenceTransformer("all-MiniLM-L6-v2", backend="onnx", model_kwargs={"export": False})

After this PR, both work as expected.

• Tom Aarsen