Fix merge problems with cherry-picking "Add notification settings to...

Fix merge problems with cherry-picking "Add notification settings to backup&restore" change into pi-dev

On 9/28 CL https://googleplex-android-review.git.corp.google.com/5116913 was checked into pi-dev. Merge was bad(couple of lines were lost during merge).

  https://b.corp.google.com/issues/35655737#comment34

Adding LOCK_SCREEN_ALLOW_PRIVATE_NOTIFICATIONS and LOCK_SCREEN_SHOW_NOTIFICATIONS to SETTINGS_TO_BACKUP array. This fixes apct/framework/presubmit test failure.

Bug: 35655737
Bug: 118674794
Test: presubmit unit tests
Change-Id: I2e9cc95e8827e72ef3c09910d4d3e089bde375e5
Merged-In: I421c7487955ee339f88e3957c973375d0f87e2ff