feat: [CI] Introduce uv to accelerate pip install (#7127)

### What this PR does / why we need it?
Integrates uv: Significantly accelerates pip install execution and
resolves concurrency issues caused by traditional pip caching
mechanisms.

Why pip install uc-manager is explicitly added:
This project depends on uc-manager. However, installing it via uv pip
install uc-manager currently fails due to a known issue. An issue has
already been filed with the upstream uv repository to address this.
Consequently, we explicitly invoke pip install uc-manager as a temporary
workaround to ensure the build succeeds.
https://github.com/ModelEngine-Group/unified-cache-management/issues/736

Why use UV_SYSTEM_PYTHON: 1:
No virtual environment has been created yet; this configuration has the
same effect as directly using `pip install`.

- vLLM version: v0.16.0
- vLLM main:
15d76f74e2

Signed-off-by: tfhddd <2272751277@qq.com>

.github/workflows/_unit_test.yaml

@@ -28,6 +28,12 @@ jobs:
         SOC_VERSION: ascend910b1
         MAX_JOBS: 4
         COMPILE_CUSTOM_KERNELS: 0
+        UV_INDEX_URL: http://cache-service.nginx-pypi-cache.svc.cluster.local/pypi/simple
+        UV_EXTRA_INDEX_URL: https://mirrors.huaweicloud.com/ascend/repos/pypi
+        UV_INDEX_STRATEGY: unsafe-best-match
+        UV_NO_CACHE: 1
+        UV_SYSTEM_PYTHON: 1
+        UV_PYTHON: python3
     steps:
       - name: Install packages
         run: |
@@ -36,6 +42,7 @@ jobs:
           pip config set global.trusted-host cache-service.nginx-pypi-cache.svc.cluster.local
           apt-get update -y
           apt-get install -y python3-pip git vim wget net-tools gcc g++ cmake libnuma-dev curl gnupg2
+          pip install uv
 
       - name: Checkout vllm-project/vllm repo
         uses: actions/checkout@v6
@@ -47,18 +54,18 @@ jobs:
       - name: Install vllm-project/vllm from source
         working-directory: ./vllm-empty
         run: |
-          VLLM_TARGET_DEVICE=empty python3 -m pip install . --extra-index https://download.pytorch.org/whl/cpu/
-          python3 -m pip uninstall -y triton
+          VLLM_TARGET_DEVICE=empty uv pip install . --extra-index-url https://download.pytorch.org/whl/cpu/
+          uv pip uninstall triton
 
       - name: Checkout vllm-project/vllm-ascend repo
         uses: actions/checkout@v6
 
       - name: Install vllm-project/vllm-ascend
         run: |
-          export PIP_EXTRA_INDEX_URL=https://mirrors.huaweicloud.com/ascend/repos/pypi
+          pip install uc-manager
           export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/Ascend/ascend-toolkit/latest/x86_64-linux/devlib
-          python3 -m pip install -v . --extra-index https://download.pytorch.org/whl/cpu/
-          python3 -m pip install -r requirements-dev.txt --extra-index https://download.pytorch.org/whl/cpu/
+          uv pip install -v . --extra-index-url https://download.pytorch.org/whl/cpu/
+          uv pip install -r requirements-dev.txt --extra-index-url https://download.pytorch.org/whl/cpu/
 
       - name: Run unit test
         env: