Run Bazel test suite on Linux ARM64 platform

Remove getStarlarkCallable() in positionalOnlyCall(). All callers of positionalOnlyCall() already pass in a StarlarkCallable.

Failed in 2m 38s
:ubuntu: Ubuntu 20.04 LTS ARM64curl -sS https://raw.githubusercontent.com/bazelbuild/continuous-integration/master/buildkite/bazelci.py?1739472099 -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?1739472099
Waited 4s
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Ran in 1m 56s
Total Job Run Time: 2m 34s