tests: Improve code coverage for rtsp-session-media
tests: Improve code coverage for rtsp-session-media

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=726940

Lachann/gst-rtsp-server,hsteinhaus/gst-rtsp-server,hsteinhaus/gst-rtsp-server,barisdemiray/gst-rtsp-server,barisdemiray/gst-rtsp-server,surround-io/gst-rtsp-server,thaytan/gst-rtsp-server,barisdemiray/gst-rtsp-server,thaytan/gst-rtsp-server,Lachann/gst-rtsp-server,Lachann/gst-rtsp-server,hsteinhaus/gst-rtsp-server,surround-io/gst-rtsp-server,thaytan/gst-rtsp-server,surround-io/gst-rtsp-server