Specify TaskScheduler.Default in EventPipeEventDispatcher (dotnet/coreclr#24930)

Just in case there's a non-default TaskScheduler in play, explicitly specify TaskScheduler.Default so that we don't accidentally schedule this task to another scheduler, in which case it's up to that scheduler if and how to respect the LongRunning request.

Commit migrated from https://github.com/dotnet/coreclr/commit/e4bbbd6ea114eda756fe7f99e29ca8d908160521

src/coreclr/src/System.Private.CoreLib/src/System/Diagnostics/Eventing/EventPipeEventDispatcher.cs

@@ -138,7 +138,7 @@ private void StartDispatchTask()
             if (m_dispatchTask == null)
             {
                 m_stopDispatchTask = false;
-                m_dispatchTask = Task.Factory.StartNew(DispatchEventsToEventListeners, TaskCreationOptions.LongRunning);
+                m_dispatchTask = Task.Factory.StartNew(DispatchEventsToEventListeners, CancellationToken.None, TaskCreationOptions.LongRunning, TaskScheduler.Default);
             }
         }