[V1][PP] Fix intermediate tensor values

[comaniac]

#13353 cached the intermediate tensors to make CUDA graph work. However, we forgot to copy the values of intermediate tensors to the cached tensors. This PR fixes it.

With this PR and #13339, I've verified that the PP is working with the correct outputs in a single node.

cc @WoosukKwon @ruisearch42

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[WoosukKwon]

Awesome! Thanks for the fix!