input: es_out: don't drain when input is stopped

When stopping an input, the player is signalled with vlc_player_Stop(), which set the input for destruction in the player destructor thread.

When we called input_Stop(), the input thread will continue running, but the demux will stop and notify the EOF state in the es_out, which was draining the decoders and the outputs despite the request to stop.

When calling input_Stop(), we are guaranteed that input_Stopped() will be true afterwards, before the EOF can be processed by the es_out, thus removing this drain.