Update VB DefineMethodOverride example to target .NET 9

Co-authored-by: gewarren <[email protected]>

Author: Copilot

snippets/visualbasic/System.Reflection.Emit/TypeBuilder/DefineMethodOverride/Project.vbproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net9.0</TargetFramework>
+  </PropertyGroup>
+
+</Project>

snippets/visualbasic/System.Reflection.Emit/TypeBuilder/DefineMethodOverride/source.vb

@@ -39,10 +39,10 @@ Class Test
         Dim name As String = "DefineMethodOverrideExample"
         Dim asmName As New AssemblyName(name)
         Dim ab As AssemblyBuilder = _
-            AppDomain.CurrentDomain.DefineDynamicAssembly( _
-                asmName, AssemblyBuilderAccess.RunAndSave)
+            AssemblyBuilder.DefineDynamicAssembly( _
+                asmName, AssemblyBuilderAccess.Run)
         Dim mb As ModuleBuilder = _
-            ab.DefineDynamicModule(name, name & ".dll")
+            ab.DefineDynamicModule(name)
 
         Dim tb As TypeBuilder = _
             mb.DefineType("C", TypeAttributes.Public, GetType(A))
@@ -84,9 +84,6 @@ Class Test
 
         Dim tc As Type = tb.CreateType()
 
-        ' Save the emitted assembly, to examine with Ildasm.exe.
-        ab.Save(name & ".dll")
-        
         Dim test As Object = Activator.CreateInstance(tc)
 
         Dim mi As MethodInfo = GetType(I).GetMethod("M")