ovs-configuration fails to start after node reboot when close to 50 transparent vlans are configured via nncp

Customer is trying to configure Transparent VLANs using NNCP policy.

There is however an issue with the nm-dispatcher scripts which causes the resolv.conf to become empty(!).

NetworkManager calls nm-dispatcher for each and every transparent vlan.
When resolv.conf is empty, the dispatcher waits for a nameserver, and eventually times out after 90 seconds.
Each vlan thereafter will cause ovs-configuration waiting for an additional 90 seconds, until a timeout is reached starting br-ex.

Eventually ovs-configuration failes with error code and while the system is 'Ready', it's unable to operate normally (eg, MCP update is stuck).


node-logs show:

```
Mar 21 13:31:57.191951 worker-0.cp-1-cluster.local nm-dispatcher[13358]: NM resolv-prepender: Prepending 'nameserver 192.168.120.46' to /etc/resolv.conf (other nameservers from /var/run/NetworkManager/resolv.conf)
Mar 21 13:31:57.349128 worker-0.cp-1-cluster.local nm-dispatcher[13513]: NM resolv-prepender: NM resolv.conf still empty of nameserver
Mar 21 13:31:57.850758 worker-0.cp-1-cluster.local nm-dispatcher[13513]: NM resolv-prepender: NM resolv.conf still empty of nameserver
...
Mar 21 13:32:26.946586 worker-0.cp-1-cluster.local nm-dispatcher[13513]: NM resolv-prepender: NM resolv.conf still empty of nameserver
Mar 21 13:32:27.486351 worker-0.cp-1-cluster.local nm-dispatcher[13662]: NM resolv-prepender: NM resolv.conf still empty of nameserver
...
Mar 21 13:32:57.086134 worker-0.cp-1-cluster.local nm-dispatcher[13662]: NM resolv-prepender: NM resolv.conf still empty of nameserver
Mar 21 13:32:57.630174 worker-0.cp-1-cluster.local nm-dispatcher[13811]: NM resolv-prepender: NM resolv.conf still empty of nameserver
...
Mar 21 13:33:04.654262 worker-0.cp-1-cluster.local nm-dispatcher[13811]: NM resolv-prepender: NM resolv.conf still empty of nameserver

Customer reproduced on their environment

1. Use the NNCP to create transparent VLANs
2. Customer refferd option C of this KBase--> https://access.redhat.com/solutions/6957685
3. They are using similar to below NNCP. Not full content

apiVersion: nmstate.io/v1
kind: NodeNetworkConfigurationPolicy
metadata: {name: 10-worker-network-vlan-data-25g-vlans}
spec:
  desiredState:
    interfaces:
    - description: data_25g.3003
      name: data_25g.3003
      state: up
      type: vlan
      vlan: {base-iface: data_25g, id: 3003}
    - bridge:
        options:
          stp: {enabled: false}
        port:
        - name: data_25g.3003
          vlan: {}
      description: data_25g_v_3003
      ipv4: {dhcp: false, enabled: false}
      ipv6: {enabled: false}
      mtu: 9000
      name: data_25g_v_3003
      state: up
      type: linux-bridge

ovs-configuration.service fails. Below are node logs

Mar 21 13:31:57.191951 worker-0.cp-1-cluster.local nm-dispatcher[13358]: NM resolv-prepender: Prepending 'nameserver 192.168.120.46' to /etc/resolv.conf (other nameservers from /var/run/NetworkManager/resolv.conf) Mar 21 13:31:57.349128 worker-0.cp-1-cluster.local nm-dispatcher[13513]: NM resolv-prepender: NM resolv.conf still empty of nameserver Mar 21 13:31:57.850758 worker-0.cp-1-cluster.local nm-dispatcher[13513]: NM resolv-prepender: NM resolv.conf still empty of nameserver ... Mar 21 13:32:26.946586 worker-0.cp-1-cluster.local nm-dispatcher[13513]: NM resolv-prepender: NM resolv.conf still empty of nameserver Mar 21 13:32:27.486351 worker-0.cp-1-cluster.local nm-dispatcher[13662]: NM resolv-prepender: NM resolv.conf still empty of nameserver ... Mar 21 13:32:57.086134 worker-0.cp-1-cluster.local nm-dispatcher[13662]: NM resolv-prepender: NM resolv.conf still empty of nameserver Mar 21 13:32:57.630174 worker-0.cp-1-cluster.local nm-dispatcher[13811]: NM resolv-prepender: NM resolv.conf still empty of nameserver ... Mar 21 13:33:04.654262 worker-0.cp-1-cluster.local nm-dispatcher[13811]: NM resolv-prepender: NM resolv.conf still empty of nameserver

ovs-configuration.service running & node getting resolv.conf populated