Fix examples

[fcogidi]

PR Type

Fix.

Short Description

• Using /model-weights/{MODEL_NAME} as the model path for completions results in the following error:

{"object":"error","message":"The model `/model-weights/Meta-Llama-3.1-8B-Instruct` does not exist.","type":"NotFoundError","param":null,"code":404}

This PR fixes the error by removing the model-weights prefix from the path.

• Additionally, most examples are updated to use Meta-Llama-3.1-8B-Instruct.

Tests Added

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