Enable label-based image test and use free runner to run lint (#2864)

### What this PR does / why we need it?
- Enable label-based image test and use free runner to run lint
- soft revert
26f388ba08

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?


- vLLM version: main
- vLLM main:
404c85ca72

Signed-off-by: Yikun Jiang <yikunkero@gmail.com>

.github/workflows/image_a3_ubuntu.yml

@@ -25,6 +25,7 @@ on:
       - 'cmake/**'
       - 'CMakeLists.txt'
       - 'csrc/**'
+    types: [ labeled ]
   push:
     # Publish image when tagging, the Dockerfile in tag will be build as tag image
     branches:
@@ -42,12 +43,18 @@ on:
       - 'cmake/**'
       - 'CMakeLists.txt'
       - 'csrc/**'
+
+# only cancel in-progress runs of the same workflow
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
 
   build:
     name: vllm-ascend image build
     runs-on: ubuntu-latest
-
+    if: ${{ contains(github.event.pull_request.labels.*.name, 'ready') && contains(github.event.pull_request.labels.*.name, 'ready-for-test') }}
     steps:
     - uses: actions/checkout@v4
       with: