Set the default state of NOTIFICATIONS_USE_RING_VOLUME.

Bug: 3365600

This doesn't affect upgrades, only new installs.

Don't backup/restore NOTIFICATIONS_USE_RING_VOLUME anymore as it doesn't
work well across device types and can wedge the device into a state
where you can never hear notification sounds.

Change-Id: I703e1db539eb4ac45b273f46ada0b4bbf3b981bb