feat: optimize getMaxWorkers using os.availableParallelism

[screetBloom]

Summary

Optimize the maximum number of worker parallelism using os.availableParallelism

os.cpus().length returns the number of CPUs in the physical device, which is static. It should be replaced with the maximum number of computations the system can execute simultaneously. In Node.js, this is provided by os.availableParallelism().

Currently, Metro requires Node.js version 18.18 or higher, which includes os.availableParallelism.

Test plan

Green CI

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@robhogan has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[screetBloom]

Additional notes:

1. The current implementation of Math.max(1, Math.ceil(cores (0.5 + 0.5 Math.exp(-cores * 0.07)) - 1)) uses approximately 50%-60% of the CPU cores, which may not achieve the highest performance in CI deployments.

2. I will try to design a method to set the optimal number of workers based on different CPU architectures in CI deployments soon. Maximize the use of all performance cores of the CI machine.

[facebook-github-bot]

@robhogan merged this pull request in facebook/metro@5ae946db8e1278395e86796d0ada8e2e57495848.