Update CI configs to be prepared for the MacOS fleet expansion.

Failed in 1m 52s
:mac: macOScurl -sS https://raw.githubusercontent.com/fweikert/continuous-integration/ms/buildkite/bazelci.py?1720214677 -o bazelci.py && python3 bazelci.py runner --task=macos --http_config=https://raw.githubusercontent.com/fweikert/bazel/macos_v2/.bazelci/postsubmit.yml
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Total Job Run Time: 3m 22s