### What this PR does / why we need it?
Fixes the issue where nightly multi-node tests hang during the "wait for
pod ready" stage due to strict shell mode.
### Does this PR introduce _any_ user-facing change?
### How was this patch tested?
- vLLM version: v0.15.0
- vLLM main:
13397841ab
Signed-off-by: MrZ20 <2609716663@qq.com>