refactor with block for sampling parameter update

[zhaochenyang20]

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What does this PR do?

I updated serval comments and the with block usage. one question left in here:

        # The format of the model weights to be loaded.
        # TODO(chenyang): why we set `load_format` to `dummy`?

        # “auto” will try to load the weights in the safetensors format and
        # fall back to the pytorch bin format if safetensors format is not
        # available.
        # “pt” will load the weights in the pytorch bin format.
        # “safetensors” will load the weights in the safetensors format.
        # “dummy” will initialize the weights with random values, which is
        # mainly for profiling.
        # “bitsandbytes” will load the weights using bitsandbytes quantization.
        # “npcache” will load the weights in pytorch format and store a numpy
        # cache to speed up the loading.

[zhaochenyang20]

Well, I am cool with the load_format. But I think seldomly do we use dummy 😂

[zyzshishui]

That's not graceful, plz roll back to single line