test-multicast2: it's not affected by setting address pool.

Submitted by Hyunjun Ko @zzoon

Link to original bug (#748518)

Description

I'm not sure if this is a bug or not.
But it's working differently with test-multicast.

Because it's not set GST_RTSP_LOWER_TRANS_UDP_MCAST to each stream,
but just each stream has default protocols GST_RTSP_LOWER_TRANS_UDP | GST_RTSP_LOWER_TRANS_UDP_MCAST | GST_RTSP_LOWER_TRANS_TCP

Does this have to be multicast when sending SDP msg?