Fix EventSource trimmer warning

src/libraries/System.Diagnostics.Tracing/ref/System.Diagnostics.Tracing.cs

@@ -145,6 +145,7 @@ public enum EventOpcode
         Send = 9,
         Receive = 240,
     }
+    [System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembersAttribute(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.All)]
     public partial class EventSource : System.IDisposable
     {
         protected EventSource() { }

src/libraries/System.Private.CoreLib/src/ILLink/ILLink.Suppressions.Shared.xml

@@ -49,12 +49,6 @@
       <property name="Scope">member</property>
       <property name="Target">M:Internal.Runtime.InteropServices.ComponentActivator.InternalGetFunctionPointer(System.Runtime.Loader.AssemblyLoadContext,System.String,System.String,System.IntPtr)</property>
     </attribute>
-    <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
-      <argument>ILLink</argument>
-      <argument>IL2072</argument>
-      <property name="Scope">member</property>
-      <property name="Target">M:System.Diagnostics.Tracing.EventSource.EnsureDescriptorsInitialized</property>
-    </attribute>
     <attribute fullname="System.Diagnostics.CodeAnalysis.UnconditionalSuppressMessageAttribute">
       <argument>ILLink</argument>
       <argument>IL2075</argument>

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

@@ -227,6 +227,9 @@ internal sealed class EventSourceAutoGenerateAttribute : Attribute
     /// }
     /// </code>
     /// </remarks>
+#if !ES_BUILD_STANDALONE
+    [DynamicallyAccessedMembers(ManifestMemberTypes)]
+#endif
     public partial class EventSource : IDisposable
     {
 
@@ -2765,7 +2768,16 @@ private void EnsureDescriptorsInitialized()
             {
                 // get the metadata via reflection.
                 Debug.Assert(m_rawManifest == null);
+#if !ES_BUILD_STANDALONE
+                [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:RequiresUnreferencedCode",
+                    Justification = "Based on the annotation on EventSource class, Trimmer will see from its analysis members " +
+                                    "that are marked with RequiresUnreferencedCode and will warn." +
+                                    "This method will not access any of these members and is safe to call.")]
+                byte[]? GetCreateManifestAndDescriptorsViaLocalMethod(string name) => CreateManifestAndDescriptors(this.GetType(), name, this);
+                m_rawManifest = GetCreateManifestAndDescriptorsViaLocalMethod(Name);
+#else
                 m_rawManifest = CreateManifestAndDescriptors(this.GetType(), Name, this);
+#endif
                 Debug.Assert(m_eventData != null);
 
                 // TODO Enforce singleton pattern