core: services: ping: Keep port watcher running after unexpected errors

[joaoantoniocardoso]

Summary

• Catch unexpected errors in the Ping PortWatcher loop so discovery keeps running.
• Add a regression test that a transient add_ping360 failure does not stop watching.

Follow-up to #4036: that PR fixes the list_ips() KeyError, but any other uncaught exception in the watch loop still permanently kills sensor discovery because sensor_manager() is started with a bare asyncio.create_task.

Test plan

• pytest core/services/ping/test_portwatcher.py
• Confirm Ping service continues discovering after SoftAP/uap0 churn on a vehicle

[joaoantoniocardoso]

Superseded by #4051 (same changes, head moved to fork joaoantoniocardoso/BlueOS-docker).

[joaoantoniocardoso]

Closed in favor of #4051.