Use a real pkg name and uid

Rather than trying to reconstruct it, as some apps use | in their tag.

Test: atest NotificationManagerServiceTest
Test: atest NotificationPermissionMigrationTest
Test: make sure an app that uses | in its tag can post notifs
Fixes: 218812985
Change-Id: Ic6332bdb827a3b603efe5b79d242bfe0bb61917d