Enable using a custom NetEqFactory in simulations

Bug: webrtc:11005
Change-Id: I8a15f77953cbd3c29a75c7cfc77f926b138994b9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/165580
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30286}

modules/audio_coding/neteq/tools/neteq_rtpplay.cc

@@ -397,7 +397,8 @@ int main(int argc, char* argv[]) {
   }
 
   std::unique_ptr<webrtc::test::NetEqTest> test =
-      factory.InitializeTestFromFile(/*input_filename=*/args[1], config);
+      factory.InitializeTestFromFile(/*input_filename=*/args[1],
+                                     /*factory=*/nullptr, config);
   RTC_CHECK(test) << "ERROR: Unable to run test";
   test->Run();
   return 0;