### What this PR does / why we need it? This PR optimizes multistream for eplb heat collection and aggregation - vLLM version: v0.12.0 - vLLM main: https://github.com/vllm-project/vllm/commit/v0.12.0 --------- Signed-off-by: daishixun <dsxsteven@sina.com> Co-authored-by: Mengqing Cao <cmq0113@163.com>