Set pytest.fixture scope to class, add Swarm E2E tests, and update Docker Swarm configurations

- Modified `pytest.fixture` scope to `class` across tests to improve fixture lifecycle and reduce setup overhead.
- Introduced a new `tests_e2e/test_swarm.py` test suite for Docker Swarm stack configurations.
- Added E2E tests for Swarm mode with scenarios such as basic services and combined plugins.
- Updated HAProxy image in Swarm stack `.yml` files to `byjg/easy-haproxy:local` for local testing consistency.
- Added `swarm` marker in `pyproject.toml` for differentiating Docker Swarm-specific tests.
- Updated GitHub workflows to include a new Swarm E2E test pipeline.

.github/workflows/build.yml

@@ -129,9 +129,33 @@ jobs:
           export PATH="$HOME/.local/bin:$PATH"
           uv run pytest tests_e2e/test_proxy_headers.py -sv --tb=short
 
+  Tests-E2E-Swarm:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    needs: [Test]
+    permissions:
+      contents: read
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        run: curl -LsSf https://astral.sh/uv/install.sh | sh
+
+      - name: Install dependencies
+        run: |
+          export PATH="$HOME/.local/bin:$PATH"
+          uv sync --group dev
+
+      - name: Run Swarm E2E tests
+        run: |
+          export PATH="$HOME/.local/bin:$PATH"
+          uv run pytest tests_e2e/test_swarm.py -sv --tb=short
+
   Build:
     runs-on: ubuntu-latest
-    needs: [Test, Tests-E2E-Docker, Tests-E2E-Kubernetes, Tests-E2E-Additional]
+    needs: [Test, Tests-E2E-Docker, Tests-E2E-Kubernetes, Tests-E2E-Additional, Tests-E2E-Swarm]
     permissions:
       contents: read
       packages: write
@@ -231,7 +255,7 @@ jobs:
 
   Publish-PyPI:
     runs-on: ubuntu-latest
-    needs: [Test, Tests-E2E-Docker, Tests-E2E-Kubernetes, Tests-E2E-Additional]
+    needs: [Test, Tests-E2E-Docker, Tests-E2E-Kubernetes, Tests-E2E-Additional, Tests-E2E-Swarm]
     if: startsWith(github.ref, 'refs/tags/')
     permissions:
       contents: read