Reduce jank when revoking notification permission

-Reorder fields so the appear/disappear more cleanly
-Remove some divider lines- they don't animate with the content, for
some reason
-Remove an unused field
-Hide the badge field (remaining field with divider) if there are no
channels
-Change style of 'Notifications are blocked' field to better match
the other fields

Test: revoke notification permission for apps with and without channels
Test: BadgePreferenceControllerTest
Fixes: 233962859
Change-Id: Ife894172bf91d838edf3b0546c5ee00e206a855f