DXF Import: fix importing circles incorrectly when unit scale is used

followup to rBA83f7e2473b7a where scaling of points was fixed (but
actually did it on the center as well -- which led to incorrect results
if center was not at the origin)

Fixes T62585

io_import_dxf/dxfimport/do.py

@@ -395,7 +395,7 @@ class Do:
             b[i].handle_left_type = 'AUTO'
             b[i].handle_right_type = 'AUTO'
 
-        vc = self.proj(en.center)
+        vc = Vector(en.center)
         clockwise = Matrix(((0, -1, 0), (1, 0, 0), (0, 0, 1)))
 
         r = major