Updates main page for Do Not Disturb

Settings > Sound > Do Not Disturb
- Update strings, more descriptive summary for DND Apps summary
- Move top-level ordering of preferences
- Remove old unused DND strings

Test: make RunSettingsRoboTests7
Test: make ROBOTEST_FILTER=ZenModeBypassingAppsPreferenceControllerTest RunSettingsRoboTests
Test: manual
Bug: 151845457
Merged-In: I9c23c558a9d764702e966d22e5c6e5c5425e4d32
Change-Id: I9c23c558a9d764702e966d22e5c6e5c5425e4d32