Clear TLS failures from observable events list on clear

Without this, they didn't appear in the UI, but they did still get used
for de-duping, and thereby hid future cert failure events.

Author: pimterry

src/model/events/observable-events-list.ts

@@ -117,6 +117,7 @@ export class ObservableEventsList {
 
         this._exchanges.clear();
         this._websockets.clear();
+        this._tlsFailures.clear();
         this._rtcConnections.clear();
         this._rtcDataChannels.clear();
         this._rtcMediaTracks.clear();