fix(generator): do not keep azure.core models

Even the accessibility is set, we should not keep them since they should be referenced from Azure.Core

resovle Azure#4597

src/AutoRest.CSharp/Common/Output/Models/Types/ModelTypeProvider.cs

@@ -48,6 +48,9 @@ internal sealed class ModelTypeProvider : SerializableObjectType
         protected override bool IsAbstract => !Configuration.SuppressAbstractBaseClasses.Contains(DefaultName) && _inputModel.DiscriminatorPropertyName is not null && _inputModel.DiscriminatorValue is null;
 
         public ModelTypeProviderFields Fields => _fields ??= EnsureFields();
+
+        public string? Namespace => _inputModel.Namespace;
+
         private ConstructorSignature InitializationConstructorSignature => _publicConstructor ??= EnsurePublicConstructorSignature();
         private ConstructorSignature SerializationConstructorSignature => _serializationConstructor ??= EnsureSerializationConstructorSignature();
 

src/AutoRest.CSharp/LowLevel/AutoRest/DpgOutputLibrary.cs

@@ -58,7 +58,7 @@ public DpgOutputLibrary(string libraryName, IReadOnlyDictionary<InputEnumType, E
 
         private IEnumerable<string>? _accessOverriddenModels;
         public IEnumerable<string> AccessOverriddenModels => _accessOverriddenModels ??= Enums.Where(e => e.IsAccessibilityOverridden).Select(e => e.Declaration.Name)
-            .Concat(Models.Where(m => m.IsAccessibilityOverridden).Select(m => m.Declaration.Name));
+            .Concat(Models.Where(m => m.IsAccessibilityOverridden && (m.Namespace == null || !m.Namespace.StartsWith("Azure.Core"))).Select(m => m.Declaration.Name));
 
         private AspDotNetExtensionTypeProvider? _aspDotNetExtension;
         public AspDotNetExtensionTypeProvider AspDotNetExtension => _aspDotNetExtension ??= new AspDotNetExtensionTypeProvider(RestClients, Configuration.Namespace, _sourceInputModel);