Revert "Fix unbalanced event handler push/pop"

This reverts commit 8ac5699fcd.

src/tracks/ui/ScrubUI.cpp

@@ -271,6 +271,7 @@ static const AudacityProject::AttachedObjects::RegisteredFactory sForwarderKey{
    []( AudacityProject &parent ){
       auto result = std::make_shared< ScrubForwarder >( parent );
       auto &window = ProjectWindow::Get( parent );
+      window.PushEventHandler( result.get() );
       return result;
    }
 };

src/tracks/ui/Scrubbing.cpp

@@ -241,6 +241,9 @@ Scrubber::~Scrubber()
    if (mpThread)
       mpThread->Delete();
 #endif
+
+   if ( mWindow )
+      mWindow->PopEventHandler();
 }
 
 static const auto HasWaveDataPred =