Remove redundant transcode tests

This was migrated to CTS and partially removed from MediaProvider in:
Ibefdad5e4cd9a645465cf74597023c0adebad37c. Some artifacts were still
left behind however.

Test: atest TranscodeTest
Bug: 169546642
Change-Id: I6cb61c49d9d803a50c1b7cabe2d5be37cb8ef5cc
1 file changed