Description

An oversight on my part in #3283. Puma::Cluster#run constantly checks if all workers have reached their idle timeout even when the feature isn't being used. This change ensures that this check only runs when idle_timeout is configured.

Also includes a micro-optimisation which ensures the idle workers state hash isn't unnecessarily initialised until actually required (either a worker indicates timeout reached via pipe or Puma::Cluster#run checks if all_workers_idle_timed_out?).

All of these changes are covered by existing tests.

Your checklist for this pull request

• I have reviewed the guidelines for contributing to this repository.
• I have added (or updated) appropriate tests if this PR fixes a bug or adds a feature.
• My pull request is 100 lines added/removed or less so that it can be easily reviewed.
• If this PR doesn't need tests (docs change), I added [ci skip] to the title of the PR.
• If this closes any issues, I have added "Closes #issue" to the PR description or my commit messages.
• I have updated the documentation accordingly.
• All new and existing tests passed, including Rubocop.