bug: liveness needs to also register_status_reason_func

[viniarck]

liveness is only registering register_status_func, and not register_status_reason_func, so only status keeps coherent, status_reason when liveness is down would be empty:

{
      "id": "4d42dc0852278accac7d9df15418f6d921db160b13d674029a87cef1b5f67f30",
      "endpoint_a": {
        "id": "00:00:00:00:00:00:00:02:3",
        "name": "s2-eth3",
        "port_number": 3,
        "mac": "66:b8:72:6c:e5:29",
        "switch": "00:00:00:00:00:00:00:02",
        "type": "interface",
        "nni": true,
        "uni": false,
        "speed": 1250000000.0,
        "metadata": {},
        "lldp": true,
        "active": true,
        "enabled": true,
        "status": "UP",
        "status_reason": [],
        "link": "4d42dc0852278accac7d9df15418f6d921db160b13d674029a87cef1b5f67f30"
      },
      "endpoint_b": {
        "id": "00:00:00:00:00:00:00:03:2",
        "name": "s3-eth2",
        "port_number": 2,
        "mac": "ce:fe:1c:d8:af:95",
        "switch": "00:00:00:00:00:00:00:03",
        "type": "interface",
        "nni": true,
        "uni": false,
        "speed": 1250000000.0,
        "metadata": {},
        "lldp": true,
        "active": true,
        "enabled": true,
        "status": "UP",
        "status_reason": [],
        "link": "4d42dc0852278accac7d9df15418f6d921db160b13d674029a87cef1b5f67f30"
      },
      "metadata": {
        "last_status_change": 1730991066.607008,
        "last_status_is_active": true,
        "notified_up_at": "2024-11-07T14:51:16.617087+00:00",
        "liveness_status": "down"
      },
      "active": true,
      "enabled": true,
      "status": "DOWN",
      "status_reason": []
    }

In terms of handling link_down|link_up notifications it's still correct, but if any application were relying only on "status_reason" here it would be a problem. That's why it's also recommended to always check if status is coherent too.

Overtime we added this option to register the reason, but it ended up left behind here for of_lldp