[cuda] manually import the correct pynvml module (#12679)
fixes problems like https://github.com/vllm-project/vllm/pull/12635 and
https://github.com/vllm-project/vllm/pull/12636 and
https://github.com/vllm-project/vllm/pull/12565
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Signed-off-by: youkaichao <youkaichao@gmail.com>