channel switching for listeners confirmed in ui before ready

problem

• when listener switches channel, the checkmark appears before the user can actually hear any audio (10+seconds for one client, depends on ice negotiation)

expected behavior

• the checkmark appears, when audio is ready, not before, not after 😉

notes

• affected version: release_220220
• witnessed this in a group test-session and we testet together
• maybe, channel selection for speakers is also affected?! cannot test myself
• maybe the echo-test-ready-requirements #131 (closed) need to be applied here?