GDScript abstract class can be created in Node/Resource creation menu

[TemporalCatcher]

Tested versions

Reproducible in: 4.5.dev5, 4.5.beta1

System information

Windows 11

Issue description

The new abstract class feature is wonderful in GDScript, but there's something I wasn't expecting to be able to do: create the node or resource of an abstract class directly from the node/resource creation menu.

What's nice is that it throws an error when I attempt to create said node/resource via the menu and doesn't attach the script, but I would like it to be unable to create it just like how the built-in and C# abstract classes do.

Steps to reproduce

1. import MRP
2. Create New Node and see you can create AbstractNode
3. Likewise, Create New Resource and see you can create AbstractResource

You may look at abstract_node.gd and abstract_resource.gd to verify that the classes are indeed abstract

Minimal reproduction project (MRP)

abstract_mrp.zip