Merge "MediaTranscoding: Use MediaPreparer to download test files" into main am: d1155c6117 am: 81ee8913d6 am: 2446c25a7f am: 140c72c3a2 am: a5dae39601

Original change: https://android-review.googlesource.com/c/platform/frameworks/av/+/2777902

Change-Id: I5fc9b02eadfb48b9205376e2164ee5603066ee57
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>