We have some (deprecated) methods that technically still return
transfer-full instances of GTypeClass's and GTypeInterface's.
The introspection scanner cannot generate bindings for them though since
it does not know how to manage their lifecycle, and we end up skipping
these symbols.
This is breaking some language bindings, and in particular gjs [1] and
lua-lgi, that were using the .ref methods.
While we should not use deprecated functions in the language bindings,
these symbols should still be introspected.
[1] https://gitlab.gnome.org/GNOME/gjs/-/issues/711
Partially reverts commit cad84d5e27.
2ce48fcb0c