video-provider,screenshare: consider a stream unhealthy only when the peer fails

Done to avoid false positives where the stream would transition to the unhealthy UI state (or flicker between states) due to disconnected also triggering it, which is not fatal. Disconnected has to be used alongside getStats heuristics, which I removed due to issues with it, so I´m hardening the transition to fatal states only

bigbluebutton-html5/imports/ui/services/bbb-webrtc-sfu/stream-state-service.js

@@ -37,7 +37,7 @@ export const unsubscribeFromStreamStateChange = (eventTag, callback) => {
 }
 
 export const isStreamStateUnhealthy = (streamState) => {
-  return streamState === 'disconnected' || streamState === 'failed' || streamState === 'closed';
+  return streamState === 'failed' || streamState === 'closed';
 }
 
 export const isStreamStateHealthy = (streamState) => {