### What this PR does / why we need it? This patch mainly doing the following things: 1. Make k8s/lws optional for multi-node testing, allowing developers to run multi-node tests locally by actively passing in the IP addresses of all nodes. 2. Allows passing a custom proxy script path in the config file to load the proxy. - vLLM version: v0.11.2 --------- Signed-off-by: wangli <wangli858794774@gmail.com>