Avoid reversing list just for the purpose of iteration. (#28393)

Author: paulomorgado

src/Servers/HttpSys/src/RequestProcessing/RequestContext.FeatureCollection.cs

@@ -616,10 +616,10 @@ private async Task NotifiyOnStartingAsync()
                 return;
             }
 
-            actions.Reverse();
             // Execute last to first. This mimics a stack unwind.
-            foreach (var actionPair in actions)
+            for (var i = actions.Count - 1; i >= 0; i--)
             {
+                var actionPair = actions[i];
                 await actionPair.Item1(actionPair.Item2);
             }
         }
@@ -707,10 +707,10 @@ private async Task NotifyOnCompletedAsync()
                 return;
             }
 
-            actions.Reverse();
             // Execute last to first. This mimics a stack unwind.
-            foreach (var actionPair in actions)
+            for (var i = actions.Count - 1; i >= 0; i--)
             {
+                var actionPair = actions[i];
                 await actionPair.Item1(actionPair.Item2);
             }
         }