Revert the changes in astral-sh/ruff#20988 and only fall back to C[Divergent] is there are actual cyclic references, not if there are simply too many layers of specialization.

In other words, prevent the Divergent type in an example like this: https://play.ty.dev/e9b94a3d-704c-4078-90fc-ed9915cfb5e7