Fix Unreported: GPencil grab tool doesn't work on strokes changed by modifiers

The grab tool in Grease Pencil sculpt mode doesn't work correctly on strokes affected by modifiers.
You had to grab over the original vertex positions to see any effect.

Pull Request: https://projects.blender.org/blender/blender/pulls/106744

source/blender/editors/gpencil_legacy/gpencil_sculpt_paint.c

@@ -1687,7 +1687,7 @@ static bool gpencil_sculpt_brush_do_frame(bContext *C,
              */
             gpencil_brush_grab_stroke_init(gso, gps_active);
             changed |= gpencil_sculpt_brush_do_stroke(
-                gso, gps_active, bound_mat, gpencil_brush_grab_store_points);
+                gso, gps, bound_mat, gpencil_brush_grab_store_points);
           }
           else {
             /* Apply effect to the stored points */