bug: trying to enable INT on an inactive EVC (currently without any paths) returns 404

[viniarck]

telemetry_int has been validating that flows exist when trying to enable INT for correctness, this is validation to ensure that the expected flows by cookies would be found, however, there's a corner case:

• mef_eline can have an inactive EVC temporarily, where it would have no flows since mef_eline always clean up the flows, so trying to enable INT should also be supported in this case. It won't install any flows, however in subsequent network convergence like link up then it would redeploy. Since now telemetry int has been supporting other network convergence, it's time to lift this restriction here, so if an inactive EVC has no flows the INT metadata should be set, but then with telemetry metadata status "DOWN".

How to reproduce

• Try to enable INT on an inactive EVC (currently without any paths) returns 404

{
    "description": "EVC 9461d30603ae44 flows not found",
    "code": 404
}

❯ http http://127.0.0.1:8181/api/kytos/mef_eline/v2/evc/9461d30603ae44 | jq            
{
  "active": false,
  "archived": false,
  "backup_path": [],
  "bandwidth": 0,
  "circuit_scheduler": [],
  "current_path": [],
  "dynamic_backup_path": true,
  "enabled": true,
  "failover_path": [],
  "id": "9461d30603ae44",
  "metadata": {},
  "name": "inter_evpl_2222",
  "primary_path": [],
  "service_level": 6,
  "uni_a": {
    "tag": {
      "tag_type": "vlan",
      "value": 2222
    },
    "interface_id": "00:00:00:00:00:00:00:01:15"
  },
  "uni_z": {
    "tag": {
      "tag_type": "vlan",
      "value": 2222
    },
    "interface_id": "00:00:00:00:00:00:00:06:22"
  },
  "sb_priority": null,
  "execution_rounds": 0,
  "owner": null,
  "queue_id": -1,
  "primary_constraints": {},
  "secondary_constraints": {},
  "primary_links": [],
  "backup_links": [],
  "start_date": "2024-04-22T13:32:18",
  "creation_time": "2024-04-22T13:32:18",
  "request_time": "2024-04-22T13:32:18",
  "end_date": null,
  "flow_removed_at": null,
  "updated_at": "2024-04-22T13:34:00"
}