feat: [sc-81850] Macos integration test

[mlataza]

Summary

Story details: https://app.shortcut.com/rewst/story/81850

• macOS integration test coverage: Added comprehensive test steps for macOS including config.json field validation, command execution and log verification, failing command error handling, debug logging level update, service stop/restart, --no-auto-updates flag verification, and syslog integration testing
• macOS syslog fix: Prefixed the service name to syslog messages (source: message) so that log show can filter entries by service name via eventMessage contains
• Wait-for-file loops: Added retry loops (up to 30s) on all three platforms (Linux, Windows, macOS) when waiting for the log file to be created after a service restart, preventing race condition failures