squash: Always get lastN value from JitsiConference instance.

modules/RTC/RTC.js

         track.conference = this.conference;
     }
 
-    /**
-     * Returns the current value for "lastN" - the amount of videos are going
-     * to be delivered. When set to -1 for unlimited or all available videos.
-     * @return {number}
-     */
-    getLastN() {
-        return this._lastN;
-    }
-
     /**
      * Get local video track.
      * @returns {JitsiLocalTrack|undefined}

modules/connectivity/ParticipantConnectionStatus.js

 
         const inP2PMode = this.conference.isP2PActive();
         const isRestoringTimedOut = this._isRestoringTimedout(id);
-        const audioOnlyMode = this.rtc.getLastN() === 0;
+        const audioOnlyMode = this.conference.getLastN() === 0;
 
         // NOTE Overriding videoMuted to true for audioOnlyMode should disable
         // any detection based on video playback or the last N.