Delete non-existing DSUB connectors
I deleted a bunch of 3D models that are no longer relevant after kicad-footprints!3583 gets merged.
The first commit has the corresponding source fix kicad-packages3D-generator!187 (merged).
The other models need a proper fix, but in contrast to footprints, doing git mv here makes no sense because the generated files would be totally different anyway.
We can in principle wait for new models to be generated and then commit new ones together with deletion of the old ones, but I don't know if there is a real need/benefit to wait.