I doubt that the path can be used for motor vehicles, as the "Ljubljana Ortophoto 2020" shows there is a bollard there. Need to check, will go there in one of the following days to see accessibility of the now-disconnected service road.

That whole area of the MDB square has been recently fully reconstructed/rebuilt. There is no road there any more, it is essentially a pedestrian zone entirely. This includes removed vegetation and parking area. Some details will need to be filled-in when the reconstruction is finished. Have you seen the square recently in person? I'll need to check how the service road you mention is now accessible by vehicles. Regards, Mark.

Oops, fixed now on both ways. It is a row of trees. A cut&paste mistake, thanks for noticing!

Fixed. Thanks fredi_alf !