CA1859 shouldn't recommend using an anonymous type as return type

### Analyzer

**Diagnostic ID**: [CA1859](https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1859): `Use concrete types when possible for improved performance`

### Analyzer source

**SDK**: 9.0.101

### Describe the bug

When a method's return type is `object` and the returned value is an anonymous type (`new { Name = "Alex" }`) the analyzer suggests changing the method's return type from `object` to ``. Of course, this return type is invalid.

### Steps To Reproduce

```csharp
Console.WriteLine(BuildObject());

private static object BuildObject() // Triggers CA1859
{
var outputData = new
{
Name = "Alex"
};

return outputData;
}
```

### Expected behavior

Shouldn't trigger the CA1859 rule.

### Actual behavior

Triggers the CA1859 rule.