Do not set ExtendedLayout on BoxedValueType (#122091)

This looks like a copy-paste mistake?

Author: MichalStrehovsky

src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/CompilerTypeSystemContext.BoxedTypes.cs

@@ -239,7 +239,7 @@ private sealed partial class BoxedValueType : MetadataType, INonEmittableType
             public override PInvokeStringFormat PInvokeStringFormat => PInvokeStringFormat.AutoClass;
             public override bool IsExplicitLayout => false;
             public override bool IsSequentialLayout => true;
-            public override bool IsExtendedLayout => true;
+            public override bool IsExtendedLayout => false;
             public override bool IsAutoLayout => false;
             public override bool IsBeforeFieldInit => false;
             public override MetadataType BaseType => (MetadataType)Context.GetWellKnownType(WellKnownType.Object);