gh-105020: Share tp_bases and tp_mro Between Interpreters For All Static Builtin Types (gh-105115)

In gh-103912 we added tp_bases and tp_mro to each PyInterpreterState.types.builtins entry.  However, doing so ignored the fact that both PyTypeObject fields are public API, and not documented as internal (as opposed to tp_subclasses).  We address that here by reverting back to shared objects, making them immortal in the process.