Don't emit manifest for NativeRuntimeEventSource (#78213)

Author: davmason

src/libraries/System.Private.CoreLib/src/System/Diagnostics/Tracing/EventSource.cs

@@ -2807,8 +2807,13 @@ private void EnsureDescriptorsInitialized()
         // Today, we only send the manifest to ETW, custom listeners don't get it.
         private unsafe void SendManifest(byte[]? rawManifest)
         {
-            if (rawManifest == null)
+            if (rawManifest == null
+                // Don't send the manifest for NativeRuntimeEventSource, it is conceptually
+                // an extension of the native coreclr provider
+                || m_name.Equals("Microsoft-Windows-DotNETRuntime"))
+            {
                 return;
+            }
 
             Debug.Assert(!SelfDescribingEvents);