GET api/{version}/deliveryservices/{id}/health returns no info if delivery service uses a topology

[mitchell852]

This Bug Report affects these Traffic Control components:

• Traffic Ops

Current behavior:

GET api/{{version}/deliveryservices/{id}/health returns no info if the delivery service uses a topology

{ "response": {
  "totalOffline": 0,
  "totalOnline": 0,
  "cachegroups": [ ]
}}

Expected behavior:

When a delivery service uses a topology, it still should have a total for all "ONLINE" and "OFFLINE" caches as well as totals for each Cache Group employed by the Topology. such as this:

{ "response": {
  "totalOffline": 16,
  "totalOnline": 388,
  "cachegroups": [
    {
      "offline": 1,
      "online": 19,
      "name": "us-fl-sarasota"
    },
    {
      "offline": 2,
      "online": 39,
      "name": "us-il-chicago"
    }
  ]
}}

Steps to reproduce:

1. Assign servers directly to a delivery service
2. GET api/{{version}}/deliveryservices/{{id}}/health and observe the online/offline counts (total and per cache group)
3. Assign a topology to the delivery service
4. GET api/{{version}}/deliveryservices/{{id}}/health and observe NO online/offline counts (total and per cache group)