Fix: GPv3: Simplify positions and radii not working

This was because the distance function was assuming that
the radii were still in the legacy `px` space rather than in the
same space as the positions.
The function wasn't updated after the merge of
07749b389d
The division by `2000.0f` can be removed.

source/blender/editors/grease_pencil/intern/grease_pencil_edit.cc

@@ -261,16 +261,12 @@ static int grease_pencil_stroke_simplify_exec(bContext *C, wmOperator *op)
         [positions, radii](int64_t first_index, int64_t last_index, int64_t index) {
           const float dist_position = dist_to_line_v3(
               positions[index], positions[first_index], positions[last_index]);
-          /* We divide the distance by 2000.0f to convert from "pixels" to an actual
-           * distance. For some reason, grease pencil strokes the thickness of strokes in
-           * pixels rather than object space distance. */
           const float dist_radii = dist_to_interpolated(positions[index],
                                                         positions[first_index],
                                                         positions[last_index],
                                                         radii[index],
                                                         radii[first_index],
-                                                        radii[last_index]) /
-                                   2000.0f;
+                                                        radii[last_index]);
           return math::max(dist_position, dist_radii);
         };