onnxruntime

fix: setting builder optimization level to TRT 8.6 default (#15897)

The actual released default level is 3 and not the previously used 2.

Just a small sample of the effects:
![Screenshot 2023-05-10 at 15 49
55](https://github.com/microsoft/onnxruntime/assets/44298237/5a694446-22c0-4943-9ddf-80670781878f)