Non-dismissibility for defaultSearchProvider

Allow notifications from the default search provider app to
be non-dismissible on unlocked devices

Test: NotificationManagerServiceTest
Test: temp change overlay for device to Notify test app; verify
behavior of ONGOING notification from the app
Fixes: 279007219

Change-Id: I7d8efbaf3307ce5b6caf766821828b0ae60e1e3c