Add missing ForwardsClientCallsAttribute (Azure#51599)

Author: live1206

eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Providers/ExtensionProvider.cs

@@ -99,7 +99,8 @@ private MethodProvider BuildRedirectMethod(CSharpType coreType, MethodProvider t
                 modifiers,
                 target.ReturnType,
                 target.ReturnDescription,
-                parameters);
+                parameters,
+                Attributes: [new AttributeStatement(typeof(ForwardsClientCallsAttribute))]);
 
             var body = new MethodBodyStatement[]
             {