### What this PR does / why we need it? 1. Fixes the environment path used to locate custom op shared libraries. 2. Uses empty tensor initialization for op outputs instead of zero-initialization for better efficiency. - vLLM version: v0.11.2 - vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.2 --------- Signed-off-by: QianChenxi <chenxi.qian.cq@outlook.com>