Automatic zen rules are always priority only

- Default automatic rules are priority only
- Existing user-created rules will be changed to priority only
- New user-created rules will always be priority only
- Metrics for new dialogs and zen preference controllers

Test: manual
Bug: 63077372
Change-Id: I8694d10ebdfa67ba96f4936c74eae17b450e32af
3 files changed