When M405 is used it changes 'volumetric_multiplier[FILAMENT_SENSOR_EXTRUDER_NUM]' value. When M406 disables M405 it leaves the value unchanged.
This PR applies 'calculate_volumetric_multipliers' in M406 instead of resetting it to 1.0 because M200 may not be compatible with M405 hence I'm sure to restore anyway with correct value.
#7504 integration has missed this part.
When more than 1 servo is used with bltouch it's impossible to predefine default servo delay for it.
In my original fix I completely removed this part but maybe this is a better compromise
GMagician