In various edge cases, this causes an assertion that was added later in
8816e1117e to be hit. The actual purpose
of the special case is not really clear. mp_seek already will change the
mpctx->stop_play value, so there shouldn't be any need to do it in
queue_seek. And it is known to cause problems so revert it. Also, remove
the special play direction logic that works around this behavior.
Fixes#13778.
This reverts commit dbdc46c97a.
d59f4fd3ec