Notify listeners of device and suggestion data together

Currently when the entry is initiated, both the device data and
suggestion data trigger updates to the UI. Since these are fetched
together, these updates should be propagated together.

Additionally, some existing tests weren't properly validating the
behaviour, and were passing due to unrelated method calls. Those tests
now properly validate the propagation of the media device.

Test: atest, manual test
Flag: com.android.systemui.enable_suggested_device_ui
Bug: 416342642
Change-Id: I703bcae32b3aff8f89395068222315dc1a898086