Move release wheel env var to Dockerfile instead (#6163)

.buildkite/release-pipeline.yaml

 steps:
   - block: "Build wheels"
 
-  - label: "Build wheel - Python {{matrix.python_version}}, CUDA {{matrix.cuda_version}}" 
+  - label: "Build wheel - Python {{matrix.python_version}}, CUDA {{matrix.cuda_version}}"
     agents:
       queue: cpu_queue
     commands:
       - "DOCKER_BUILDKIT=1 docker build --build-arg max_jobs=16 --build-arg USE_SCCACHE=1 --build-arg CUDA_VERSION={{matrix.cuda_version}} --build-arg PYTHON_VERSION={{matrix.python_version}} --tag vllm-ci:build-image --target build --progress plain ."
       - "mkdir artifacts"
-      - "docker run --rm -v $(pwd)/artifacts:/artifacts_host -e CMAKE_BUILD_TYPE=Release vllm-ci:build-image cp -r dist /artifacts_host"
+      - "docker run --rm -v $(pwd)/artifacts:/artifacts_host vllm-ci:build-image cp -r dist /artifacts_host"
       - "aws s3 cp --recursive artifacts/dist s3://vllm-wheels/$BUILDKITE_COMMIT/"
     matrix:
       setup:

Dockerfile

@@ -99,6 +99,7 @@ RUN --mount=type=cache,target=/root/.cache/pip \
         && rm -rf sccache.tar.gz sccache-v0.8.1-x86_64-unknown-linux-musl \
         && export SCCACHE_BUCKET=vllm-build-sccache \
         && export SCCACHE_REGION=us-west-2 \
+        && export CMAKE_BUILD_TYPE=Release \
         && sccache --show-stats \
         && python3 setup.py bdist_wheel --dist-dir=dist \
         && sccache --show-stats; \