Improved generation of audio thumbnails.

This finishes migration of audio thumbnail generation to mirror how
image and video thumbnails are generated.  It also removes a bunch
of crufty code, shifting the logic for resolving an audio thumbnail
over to ThumbnailUtils, where it belongs.

Bug: 63440459, 119887587
Test: atest cts/tests/tests/media/src/android/media/cts/MediaScanner*
Test: atest cts/tests/tests/provider/src/android/provider/cts/MediaStore*
Change-Id: I4e3ebe8aaac09c7676b3427c2ba0d8d22039cb80
1 file changed