Avoid stalled macOS PHP setup watchdog cleanup

[rmcdaniel]

Summary

Use the pinned PHP setup action's supported Homebrew watchdog opt-out on macOS. Preserve the ten-minute whole-step timeout, PHP version, extensions, action pin and all actual native launcher tests. Linux retains the action's default watchdog setting.

Refs #39 and #42. Immutable CLI 2.2.3 source/tag remains unchanged.

Evidence

Release run 38102452772 passes Linux x86_64, Linux aarch64, Windows and PHAR. Mac PHP setup produces only its startup header and then reaches the ten-minute step timeout. It terminates normally and retains logs, unlike the earlier force-cancelled attempts.

The pinned action predates upstream Homebrew timeout cleanup and retry propagation correction. A bounded process reproduction using the exact two helper versions demonstrates the pinned reader/descendant cleanup hanging beyond an eight-second outer limit. The corrected upstream helper returns its expected timeout in three seconds. An initial minimal container lacked pgrep and was discarded as an unqualified runner. The comparison uses a container with pgrep and actual subprocesses/FIFOs.

The Mac log does not identify which Homebrew operation stalled. This change removes the demonstrated faulty helper from that setup path without adopting a new action version or weakening physical launcher qualification. Normal checks and a fresh actual Mac run must pass before publication.