Preconditions: Enable realtime collaboration for the WYSIWYG editor

• As Admin click on Drawer > Administer Wiki > Editing > WYSIWYG Editor
• Remove (uncheck) the "xwiki-realtime" from the list of disabled plugins in the CKEditor administration section
• Click on the Save button

Steps to reproduce:

1. As a simple user (user01) edit any page
2. Open a new private (incognito) browser window and login with another simple user (user02)
3. Access the same page and edit it, forcing the lock
4. Untick "Allow Realtime Collaboration"
5. Click on the "Leave the collaborative session" button
6. Click Save & View
7. Edit the page again

Expected results: The Realtime Collaboration remains deselected until the user checks it again.

Actual results:  The "Allow Realtime Collaboration" functionality remains even when the checkbox is unticked.