yuzu-cmd/yuzu: Replace direct usage of the global system telemetry accessor in main()

We already have the system instance around, so we can use that instead
of the accessor.

src/citra/citra.cpp

@@ -374,7 +374,7 @@ int main(int argc, char** argv) {
         break; // Expected case
     }
 
-    Core::Telemetry().AddField(Telemetry::FieldType::App, "Frontend", "SDL");
+    system.TelemetrySession().AddField(Telemetry::FieldType::App, "Frontend", "SDL");
 
     if (use_multiplayer) {
         if (auto member = Network::GetRoomMember().lock()) {