video-split: remove dummyrtpsession

Before Video-split we needed a dummy rtp session in order to show audio only participants in the conference ui. With the mentioned change, we can now remove this dummy session.

assigned to @agsantos

added sprintto review + 1 deleted label

changed title from video-split: remove dummystpsession to video-split: remove dummyrtpsession

changed the description

mentioned in commit a6e0119c

removed sprintto review label

closed