[Layout] Default value for app display (section)

[srenault-meeds]

Is your feature request related to a problem? Please describe.
Given editing a page
When editing a section
Then I can decide to make the app sticky when scrolling down

Problem: It is not set as default. Indeed, admins need to know it to precise this behaviour

Describe the solution you'd like
Default value for behaviour when scrolling down set to 'Last app in the column'