The WebPreferences page that is created following a save of rules on a space reference is not hidden

Steps to reproduce:

• create a page (non-terminal)
• make sure to not access its "Page administration" menu at all
• using the rights api, save a bunch of rules on the space reference that corresponds to the non-terminal page

Expected result:

• the WebPreferences page that is created to store the rights on is a hidden page, like all Web Preferences pages

Actual result:

• the WebPreferences page is not hidden it can be seen in the pages tree by all users, regardless of their hidden pages preferences