[CI] Migrate e2e test runner to hk (#5344)

### What this PR does / why we need it?
This patch add new runner labels for the HK region, and e2e single-card
testing has been migrated to this runner.

- vLLM version: release/v0.13.0
- vLLM main:
bc0a5a0c08

---------

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

.github/actionlint.yaml

@@ -21,3 +21,7 @@ self-hosted-runner:
     - linux-aarch64-a3-0
     - linux-amd64-cpu-8-hk
     - linux-amd64-cpu-16-hk
+    - linux-aarch64-a2b3-0
+    - linux-aarch64-a2b3-1
+    - linux-aarch64-a2b3-2
+    - linux-aarch64-a2b3-4