The new pairing page includes new UI for "See more devices" buttton and
can show MFi + ASHA devices in the pairing list while these devices only
advertise MFi HAS uuid in pairing mode.
As allowed by "Flag Cleanup Policy", this change finishes the rollout of trunkfood flag new_hearing_device_pairing_page by defaulting to the "true" state.
Bug: 307473972
Test: atest HearingAidPairingDialogFragmentTest
Test: atest AddDevicePreferenceControllerTest
Change-Id: I6c3377d535139d62791548557c581317d1878e9d
6e78a34d9c