stopping the glb-director-xdp service does not stop directing traffic

Executing this does not stop traffic being directed:
```
sudo systemctl stop glb-director-xdp.service xdp-root-shim@enp0s20f0.service
```
but this does:
```
sudo ip link set enp0s20f0 xdp off
```

Traffic is then resumed with:
```
systemctl start glb-director-xdp.service xdp-root-shim@enp0s20f0.service
```

Perhaps glb-director-xdp or the xdp-root-shim should be pro-actively removing the xdp object on service stop?