Use consolidated zen policy for dnd

Instead of using the default notification policy,
use the consolidated zen policy when do not disturb
is in priority only dnd mode

Bug: 111474881
Test: atest ZenModeHelperTest ZenPolicyTest ZenModeFilteringTest AudioManagerTest
Test: atest SystemUITests ZenModeExtractorTest
Change-Id: I88934103a56f06d4a4f620a8f557347331a79627