fix(TPC) add muted tracks if p2p is disabled (fix #1851)

modules/RTC/TraceablePeerConnection.js

 
     if (this._usesUnifiedPlan) {
         logger.debug(`${this} TPC.addTrack using unified plan`);
-        if (webrtcStream) {
+        if (webrtcStream || !this.isP2P) {
             try {
                 this.tpcUtils.addTrack(track, isInitiator);
             } catch (error) {