incusd/network/ovn: Handle chassis group having been deleted

This case happens when a network was deleted by the cluster leader but
some other servers in the cluster are yet to stop the network and remove
themselves as chassis in the HA group.

Closes lxc#709

Signed-off-by: Stéphane Graber <stgraber@stgraber.org>

internal/server/network/driver_ovn.go

@@ -2698,7 +2698,7 @@ func (n *ovn) deleteChassisGroupEntry() error {
 	}
 
 	err = n.state.OVNNB.SetChassisGroupPriority(context.TODO(), n.getChassisGroupName(), chassisID, -1)
-	if err != nil {
+	if err != nil && err != ovs.ErrNotFound {
 		return fmt.Errorf("Failed deleting OVS chassis %q from chassis group %q: %w", chassisID, n.getChassisGroupName(), err)
 	}