Simplify ShouldIGnoreBeOperationName because it's ~15 times faster

| Method           | Mean      | Error     | StdDev    | Allocated |
|----------------- |----------:|----------:|----------:|----------:|
| ArrayBasedUpdate | 30.029 us | 0.1795 us | 0.1402 us |         - |
| PairBasedUpdate  |  2.815 us | 0.0232 us | 0.0206 us |         - |

Author: andrewlock

tracer/src/Datadog.Trace/Activity/Handlers/ActivityHandlerCommon.cs

@@ -157,7 +157,7 @@ public static void ActivityStarted<T>(string sourceName, T activity, OpenTelemet
                 }
 
                 // We check if we have to ignore the activity by the operation name value
-                if (IgnoreActivityHandler.ShouldIgnoreByOperationName(activity))
+                if (IgnoreActivityHandler.ShouldIgnoreByOperationName(activity.OperationName))
                 {
                     IgnoreActivityHandler.IgnoreActivity(activity, Tracer.Instance.ActiveScope?.Span as Span);
                     activityMapping = default;
@@ -216,7 +216,7 @@ public static void ActivityStopped<T>(string sourceName, T activity)
             {
                 if (activity.Instance is not null)
                 {
-                    if (IgnoreActivityHandler.ShouldIgnoreByOperationName(activity))
+                    if (IgnoreActivityHandler.ShouldIgnoreByOperationName(activity.OperationName))
                     {
                         return;
                     }

tracer/src/Datadog.Trace/Activity/Handlers/IgnoreActivityHandler.cs

@@ -5,6 +5,7 @@
 
 #nullable enable
 
+using System;
 using Datadog.Trace.Activity.DuckTypes;
 using Datadog.Trace.Util;
 
@@ -30,24 +31,13 @@ internal sealed class IgnoreActivityHandler : IActivityHandler
             "Experimental.System.Net.Sockets",
         };
 
-        private static readonly string[] IgnoreOperationNamesStartingWith =
+        public static bool ShouldIgnoreByOperationName(string? operationName)
         {
-            "System.Net.Http.",
-            "Microsoft.AspNetCore.",
-        };
-
-        public static bool ShouldIgnoreByOperationName<T>(T activity)
-            where T : IActivity
-        {
-            foreach (var ignoreSourceName in IgnoreOperationNamesStartingWith)
-            {
-                if (activity.OperationName?.StartsWith(ignoreSourceName) == true)
-                {
-                    return true;
-                }
-            }
-
-            return false;
+            // We only have two ignored operation names for now, if we get more, we can be more
+            // generalized, but this is called twice in hot path creation
+            return operationName is not null
+                && (operationName.StartsWith("System.Net.Http.", StringComparison.Ordinal)
+                 || operationName.StartsWith("Microsoft.AspNetCore.", StringComparison.Ordinal));
         }
 
         public static void IgnoreActivity<T>(T activity, Span? span)