when importing a layout from creation to view, custom properties are created

see attached screenshot

Steps to reproduce;

• add a "vocabulary" widget to the creation layout and configure its properties (required, etc...)
• in the view layout, import the creation layout
• the widget custom properties are filled with the non-existing properties in this mode

Other use case:

• add a "vocabulary" widget to the creation layout and configure its properties (required, etc...)
• make it read only
• the cutom properties in view mode are filled with the non-existing properties in this mode