Add-ons for non-appointable products should not have the duration box

[Valentina R]

Since there is no duration for non-appointable products it only confuses customers. Removing/hiding the duration would be the solution.

Reported here: [https://bookingwp.com/forums/topic/add-ons-checkbox-options-not-displaying-properly/](https://bookingwp.com/forums/topic/add-ons-checkbox-options-not-displaying-properly/)

[Željan Topić]

Cannot reproduce.