fix(conference) Remove the check for multi-stream mode for web client.

conference.js

@@ -55,10 +55,7 @@ import {
     p2pStatusChanged,
     sendLocalParticipant
 } from './react/features/base/conference';
-import {
-    getMultipleVideoSendingSupportFeatureFlag,
-    getReplaceParticipant
-} from './react/features/base/config/functions';
+import { getReplaceParticipant } from './react/features/base/config/functions';
 import {
     checkAndNotifyForNewDevice,
     getAvailableDevices,
@@ -1422,9 +1419,7 @@ export default {
                     return;
                 }
 
-                // In the multi-stream mode, add the track to the conference if there is no existing track, replace it
-                // otherwise.
-                if (getMultipleVideoSendingSupportFeatureFlag(state)) {
+                // Add the track to the conference if there is no existing track, replace it otherwise.
                 const trackAction = oldTrack
                     ? replaceLocalTrack(oldTrack, newTrack, room)
                     : addLocalTrack(newTrack);
@@ -1439,21 +1434,6 @@ export default {
                         reject(error);
                     })
                     .then(onFinish);
-
-                    return;
-                }
-                APP.store.dispatch(
-                    replaceLocalTrack(oldTrack, newTrack, room))
-                    .then(() => {
-                        this._setSharingScreen(newTrack);
-                        this.setVideoMuteStatus();
-                    })
-                    .then(resolve)
-                    .catch(error => {
-                        logger.error(`useVideoStream failed: ${error}`);
-                        reject(error);
-                    })
-                    .then(onFinish);
             });
         });
     },