Remove the tpu docker image nightly build. (#27997)

Signed-off-by: Qiliang Cui <derrhein@gmail.com>

.buildkite/release-pipeline.yaml

@@ -116,24 +116,6 @@ steps:
     commands:
       - "bash .buildkite/scripts/annotate-release.sh"
 
-  - label: "Build and publish TPU release image"
-    depends_on: ~
-    if: build.env("NIGHTLY") == "1"
-    agents:
-      queue: tpu_queue_postmerge
-    commands:
-      - "yes | docker system prune -a"
-      - "git fetch --all"
-      - "DOCKER_BUILDKIT=1 docker build --build-arg max_jobs=16 --build-arg USE_SCCACHE=1 --build-arg GIT_REPO_CHECK=1 --tag vllm/vllm-tpu:nightly --tag vllm/vllm-tpu:$BUILDKITE_COMMIT --progress plain -f docker/Dockerfile.tpu ."
-      - "docker push vllm/vllm-tpu:nightly"
-      - "docker push vllm/vllm-tpu:$BUILDKITE_COMMIT"
-    plugins:
-      - docker-login#v3.0.0:
-          username: vllmbot
-          password-env: DOCKERHUB_TOKEN
-    env:
-      DOCKER_BUILDKIT: "1"
-
   - input: "Provide Release version here"
     id: input-release-version
     fields: