What does this PR do ?

Gemma models were broken in NeMo-RL and vLLM by this HF commit: huggingface/transformers#37033. To address this:

• Patch vllm to include gemma change from this PR: [Bugfix] Update multimodel models mapping to fit new checkpoint after Transformers v4.52 vllm-project/vllm#19151
• Fix Gemma parallelism in NeMo-RL that was broken by model_prefix change

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