SDSTOR-13146 : Update AM's /api/v1/utilization endpoint

[shosseinimotlagh]

change utilization format:

curl http://localhost:5000/api/v1/utilization | jq .

Sample output:

{
  "partitions": [
    {
      "id": "09a5cba0-49d6-4398-97ed-f85972a30087",
      "usedCapacity": 4943872
    },
    {
      "id": "32eb6671-42ca-4452-8592-05a1dfe108e1",
      "usedCapacity": 333242368
    },
    {
      "id": "600a0834-be08-414a-a8c4-d7b47469e5a5",
      "usedCapacity": 5619712
    },
    {
      "id": "ba7a1236-1a79-4cf7-8d40-cb3c38b10c81",
      "usedCapacity": 339243008
    }
  ]
}

[d2chau]

LGTM