Description of problem:
Removing simpleMacvlanConfig from CNO not delete old network-attachment-definition

Version-Release number of selected component (if applicable):
4.2.0-0.nightly-2019-09-25-043501

How reproducible:
Always

Steps to Reproduce:
1. using simpleMacvlanConfig to create network-attach-def through CNO 
2. Check  network-attach-def is created
3. Edit CNO to remove simpleMacvlanConfig
4. After 21 minutes, network-attach-def is not deleted

Actual results:
[root@dhcp-41-193 FILE]# oc get networks.operator.openshift.io cluster -o yaml
apiVersion: operator.openshift.io/v1
kind: Network
metadata:
  creationTimestamp: "2019-09-25T14:51:10Z"
  generation: 8
  name: cluster
  resourceVersion: "57016"
  selfLink: /apis/operator.openshift.io/v1/networks/cluster
  uid: e9edd716-dfa3-11e9-adea-028a60c357e8
spec:
  additionalNetworks:
  - name: macvlan-ipam-static
    namespace: test1
    simpleMacvlanConfig:
      ipamConfig:
        staticIPAMConfig:
          addresses:
          - address: 22.2.2.2/24
            gateway: 22.2.2.254
        type: static
      master: ens5
      mode: bridge
    type: SimpleMacvlan
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23
  defaultNetwork:
    type: OpenShiftSDN
  serviceNetwork:
  - 172.30.0.0/16
status: {}
[root@dhcp-41-193 FILE]# oc get network-attachment-definition --all-namespaces
NAMESPACE   NAME                  AGE
test1       macvlan-ipam-static   6s
[root@dhcp-41-193 FILE]# oc edit networks.operator.openshift.io cluster
network.operator.openshift.io/cluster edited
[root@dhcp-41-193 FILE]# oc get networks.operator.openshift.io cluster -o yaml
apiVersion: operator.openshift.io/v1
kind: Network
metadata:
  creationTimestamp: "2019-09-25T14:51:10Z"
  generation: 11
  name: cluster
  resourceVersion: "63895"
  selfLink: /apis/operator.openshift.io/v1/networks/cluster
  uid: e9edd716-dfa3-11e9-adea-028a60c357e8
spec:
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23
  defaultNetwork:
    type: OpenShiftSDN
  serviceNetwork:
  - 172.30.0.0/16
status: {}
[root@dhcp-41-193 FILE]# oc get network-attachment-definition --all-namespaces
NAMESPACE   NAME                  AGE
test1       macvlan-ipam-static   5m59s
[root@dhcp-41-193 FILE]# oc get network-attachment-definition --all-namespaces
NAMESPACE   NAME                  AGE
test1       macvlan-ipam-static   21m

Expected results:
macvlan-ipam-static should be deleted

Additional info: