Delete artifacts of interfaces not managed any more

[murinicanor]

if i create a bridge using debops.ifupdown

        ifupdown__interfaces: {                                                                                                              
          'foobar': {
            type: bridge,
            inet: 'static',
            address: '10.2.2.2/25' }
          }

and later remove that bridge, the interface-file does not get removed from /etc/network/interfaces.config.d (and /etc/network/interfaces.d). maybe the directory should be purged before interface-files are being created