Make non-blockable notification more robust

By keeping track of them in preferenceshelper, so
they can be applied to apps/channel settings created on the
first boot post a factory reset

Test: atest
Bug: 140893722
Change-Id: Ied7d66bd4ca59f831fc77eff3ef6030a1ad8d6f7
(cherry picked from commit 204b391f)
(cherry picked from commit 046114dc)