Run Bazel test suite on Linux ARM64 platform

Fix a bug which makes WorkerPool create too many workers and go above the limitation.

Failed in 3m 39s
:ubuntu: Ubuntu 20.04 LTS ARM64curl -sS https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/bazelci.py?1739197366 -o bazelci.py && python3.8 bazelci.py runner --task=ubuntu2004_arm64 --http_config=https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/pipelines/bazel-linux-arm64.yml?1739197366
Waited 7s
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Ran in 2m 53s
Total Job Run Time: 3m 32s