Try fix EventRoute weak memory leak (#9463)

Fixes #9467

GC is not reclaiming WPF control objects when they are removed from the visual tree, if tracing is enabled in a WPF application. 

This issue came from PR : Reduce allocations when tracing routed events by bgrainger · Pull Request #6700 · dotnet/wpf, a performance improvement for applications using tracing, by removing unnecessary allocations. However, while doing that, we don't clear the array which causes this issue. However, eventually these control objects are collected.

Author: lindexi

src/Microsoft.DotNet.Wpf/src/PresentationCore/System/Windows/EventRoute.cs

@@ -200,9 +200,9 @@ private void InvokeHandlersImpl(object source, RoutedEventArgs args, bool reRais
                             TraceEventType.Stop,
                             TraceRoutedEvent.InvokeHandlers,
                             _traceArguments);
-                    }
-
 
+                        Array.Clear(_traceArguments);
+                    }
                 }
             }
             else
@@ -273,6 +273,8 @@ private void InvokeHandlersImpl(object source, RoutedEventArgs args, bool reRais
                                 TraceEventType.Stop,
                                 TraceRoutedEvent.InvokeHandlers,
                                 _traceArguments);
+
+                            Array.Clear(_traceArguments);
                         }
 
                     }