[CI] Update pytest command to exclude specific test in nightly build (#2272)

.buildkite/test-nightly.yml

@@ -77,7 +77,7 @@ steps:
     if: build.env("NIGHTLY") == "1" || build.pull_request.labels includes "nightly-test"
     commands:
       - export VLLM_WORKER_MULTIPROC_METHOD=spawn
-      - pytest -s -v tests/e2e/online_serving/test_*_expansion.py --ignore tests/e2e/online_serving/test_wan22_expansion.py -m "advanced_model and diffusion and H100" --run-level "advanced_model"
+      - pytest -s -v tests/e2e/online_serving/test_*_expansion.py -k "not test_wan22_expansion" -m "advanced_model and diffusion and H100" --run-level "advanced_model"
     agents:
       queue: "mithril-h100-pool"
     plugins: