Auto-arrange centered the pile on `best_object_pos`, so on printers with an off-center position (A1 mini, H2C, H2D, H2D Pro, X2D) a large pile could end up partly off the bed. The final alignment now always clamps the pile to the bed, and the `clamp_to_bin` flag is removed. Belt printers already clamped, and centered alignment is unchanged.
The check against fixed parts and excluded regions now tests the position the pile is actually moved to.
Fixes#15727