Identify the RouteAgent instance when logging failed connections for diagnose

[tpantelis]

The output from subctl diagnose for a failed connect shows:

✗ Checking route agent connections
✗ Connection to cluster "ocp-dr-mz" is not established. Connection details:
{
  "status": "error",
  "statusMessage": "Failed to successfully ping the remote endpoint IP \"242.1.255.244\"",
  ...
  }
}

However, there can be many route-agents so it's useful to see which route-agent it's referring to.

I propose:

✓ Retrieving route agents
✓ Checking connections for route agent "worker1"
✗ Checking connections for route agent "worker2"
✗ Connection to cluster "ocp-dr-mz" is not established. Connection details:
{
  "status": "error",
  "statusMessage": "Failed to successfully ping the remote endpoint IP \"242.1.255.244\"",
  ...
  }
}