Remove transcoding for apps from Settings.

Now that we are reading the transcode_compat_manifest from DeviceConfig,
we don't need the app-level transcode settings under Media transcoding
settings.  So, removing the string.

BUG=169327180
Test: manual testing.

Change-Id: I95c2d15f7645b5aadc40283dd83d45fd14f87d88
1 file changed