`M204` is often used by slicers to set acceleration depending on perimeter, infill, etc., so Marlin's answers are flooding the serial windows. Silence `M204` according to the philosophy that setter commands should only send a reply if no parameter is given.
Missed in the original LA 1.5 PR: eISR has to use a local copy of
current_block->use_advance_lead because it might still run wenn the last
block has been set to NULL.
Sebastianv650