DO NOT MERGE: More tests for CurrentUserContextTracker

Reworks some of the CurrentUserContextTracker and test its
functionality, and consequently fixes some NotificationConversationInfo
tests

Test: atest CurrentUserContextTrackerTest NotificationConversationInfoTest
Bug: 151843296
Fixes: 154332812
Change-Id: I0e3d4b1c64cba2cab581abca4ce9377a7c4676de
6 files changed