Fixed the appearance of the heads up statusbar view on the lockscreen

The text is now based on the sensitivity of the notifications which
also makes sure that dynamic privacy and other functions work
properly and aren't based on the global public device state
but individual.

Bug: 130327302
Test: add hun on lockscreen, observe correct text
Change-Id: I26a12ff6395dbbfb30bf87f0da1fa0a951edec94