Fix 500 when fetching tracks from Apache+S3 (#1979)

This (locally) fixes #1979 (closed). Someone with more familiarity should really look at it, though: there's some asymmetry in funkwhale_api/music/views.py between nginx and apache2 which I don't entirely understand, so I'm not sure how safe this is. It also seems like this was an intentional change in 300e24db. But also, the test introduced in that change, test_serve_file_in_place, doesn't work for me locally despite the rest of the tests being green ... so ... 🤷 ?