Skip unused Bazel install in benchmark Docker image

[Copilot]

The benchmark GitHub Actions job fails while building benchmark/Dockerfile because the pinned mimalloc-bench setup script downloads a Bazel GPG key from a URL that now returns 404.

• Benchmark image setup

  • Patches the pinned mimalloc-bench script during the Docker build.
  • Removes the standalone aptinstallbazel call before running ./build-bench-env.sh packages.
  • Keeps the pinned mimalloc-bench revision unchanged.

• Scope of change

  • Bazel is only needed for the tcg benchmark path.
  • This Dockerfile builds and runs the configured benchmark workloads against snmalloc only, so the Bazel install is unused in this job.

RUN sed -i '/^[[:space:]]*aptinstallbazel[[:space:]]*$/d' build-bench-env.sh && \
    if grep -q '^[[:space:]]*aptinstallbazel[[:space:]]*$' build-bench-env.sh; then \
      echo "failed to remove unused Bazel install"; \
      exit 1; \
    fi