Gloo upstream group not working with discovery disabled

[stefanprodan]

Gloo 0.20.x is not working with upstream groups without the discovery service:

  kind: VirtualService
    generation: 3
    name: podinfo
    namespace: gloo-system
    resourceVersion: "947"
    selfLink: /apis/gateway.solo.io/v1/namespaces/gloo-system/virtualservices/podinfo
    uid: f3729a2b-8014-49e8-9981-0a2b7a76c807
  spec:
    virtualHost:
      domains:
      - '*'
      name: podinfo
      routes:
      - matcher:
          prefix: /
        routeAction:
          upstreamGroup:
            name: podinfo
            namespace: test
  status:
    reported_by: gateway
    state: 1
    subresource_statuses:
      '*v1.Proxy gloo-system gateway-proxy-v2':
        reason: "warning: \n  Route Warning: InvalidDestinationWarning. Reason: invalid
          destination in weighted destination list: *v1.Upstream {test-podinfo-primary-9898
          gloo-system} not found"
        reported_by: gloo
        state: 3

  apiVersion: gloo.solo.io/v1
  kind: UpstreamGroup
  metadata:
    generation: 2
    name: podinfo
    namespace: test
    ownerReferences:
    - apiVersion: flagger.app/v1alpha3
      blockOwnerDeletion: true
      controller: true
      kind: Canary
      name: podinfo
      uid: bedfec33-8c21-45ab-8fa9-2a32beeaa0ed
    resourceVersion: "944"
    selfLink: /apis/gloo.solo.io/v1/namespaces/test/upstreamgroups/podinfo
    uid: 1498c560-da37-476c-be75-3368769fbc0e
  spec:
    destinations:
    - destination:
        upstream:
          name: test-podinfo-primary-9898
          namespace: gloo-system
      weight: 100
    - destination:
        upstream:
          name: test-podinfo-canary-9898
          namespace: gloo-system
  status:
    reason: "2 errors occurred:\n\t* destination # 1: upstream not found: list did
      not find upstream gloo-system.test-podinfo-primary-9898\n\t* destination # 2:
      upstream not found: list did not find upstream gloo-system.test-podinfo-canary-9898\n\n"
    reported_by: gloo
    state: 2