[CI] Show disk usage for CI shared volume (#5821)

### What this PR does / why we need it?
1. Remove some useless but too large models from the shared volume
2. Add a new step to show current usage


- vLLM version: v0.13.0
- vLLM main:
2f4e6548ef

---------

Signed-off-by: wangli <wangli858794774@gmail.com>

.github/workflows/labled_download_model.yaml

@@ -30,6 +30,10 @@ jobs:
           pip config set global.index-url https://mirrors.tuna.tsinghua.edu.cn/pypi/web/simple
           pip install modelscope
 
+      - name: Show Current Disk Usage
+        run: |
+          df -h /root/.cache | grep -v Filesystem | \
+          awk '{print "Mount point: "$6, "Total: "$2, "Used: "$3, "Available: "$4, "Usage: "$5}'
       - name: Checkout PR branch
         uses: actions/checkout@v6
         with: