When using the --playlist option on the commandline, it would mark all
entries on the command as having the playlist-path of the value of that
passed option, not just the ones that were expanded from it. Fix this by
moving the playlist_populate_playlist_path to the same place where the
playlist file gets expanded.
Ref https://github.com/mpv-player/mpv/issues/13075#issuecomment-1852179164