Coffee machine examples sugar slider does not reset sugarAmount when backing from one of the selected coffee type pages.

In Coffee select page, select one of the coffee types.
Change value of the sugar slider and go back to the selection page.
Re-select coffee type and press start button -> continue.
During and after the loading sugar image can be seen in the cup image.
-in linked video you can seen that slider says 0p but on the next pages sugar image is shown

if the slider shows 0 sugar image should not be visible.
Tested whit Squish test QTBUG-138433.

• Slider value show properly but sugarAmount is only updated when the slider has been moved.