Add per validator logs for connected + disconnected

[ceyonur]

We currently log them in debug, but we should at least log validator connected/disconnected in a higher(info) level.

[github-actions[bot]]

This issue has become stale because it has been open 60 days with no activity. Adding the lifecycle/frozen label will cause this issue to ignore lifecycle events.

[joshua-kim]

This could be a dos concern if a validator keeps flipping on/off. Closing.