Fix broken playlist tests.

MediaProvider will be creating the DATA path automatically, so the
caller shouldn't specify an invalid path.

Also fix bug in test media, since "mp3_3" doesn't resolve to a valid
MIME type.

Bug: 132359020, 143549606
Test: atest --test-mapping packages/providers/MediaProvider
Change-Id: If759e8e8742d51dc8ac4b32b4fe5c845a67a8a75
3 files changed