Fix linux-sysmonitor compatibility issues inside Docker container

[PuneethM-06]

Containerization exposed several runtime assumptions in the health-check script that prevent it from behaving consistently inside a Docker container.

Observed Issues

• CPU usage parsing fails because the output format of top differs inside the container.
• journalctl is unavailable because standard Docker containers do not run systemd.
• Ensure the script produces the same output in both native Linux and Docker environments.

Acceptance Criteria

• CPU usage is parsed reliably across environments.
• Script gracefully handles environments without systemd/journalctl.
• Docker output matches native execution.
• No runtime errors are displayed.