There's no reason for G28 to reset DUAL_NOZZLE_DUPLICATION_MODE, because it only affects the E stepper, unlike DUAL_X_CARRIAGE which affects the X steppers as well.
- Add configuration support for zigzags in either the X or Y axis, for
wipe pads significantly longer in one dimension.
- Add configuration for default number of zig-zag triangles, vs. a
magic number in `Marlin_main.cpp`.
- Update description of auto nozzle wiping to match functionality