Fix issue where clings didn't appear after set up wizard (issue 13077829)

-> Also removed the db-created as a criteria for showing the clings
   (this was a bit problematic in some cases and going forward)
-> Instead, we use database upgrade as a signal to not show the clings.
   This is used instead of the above criteria (to prevent old users from
   seeing the migration cling and losing their data.)
-> Stripped some old code related to custom clings that's no longer used.

Change-Id: Ib5e5285e5ddbc60e69eb998ee9fd092ae879150d