fix(rn) release audioVideo stream after creating new MediaStream

The old stream needs to be released while keeping the tracks intact

modules/RTC/RTCUtils.js

                     videoStream.addTrack(videoTracks[j]);
                 }
             }
+
+            audioVideo.release && audioVideo.release(false);
         } else {
             // On other types of browser (e.g. Firefox) we choose (namely,
             // obtainAudioAndVideoPermissions) to call getUserMedia per device