[ty] Guard descriptor classification cycles (#26690)
## Summary
Our data-descriptor predicates recursively inspect outer unions,
intersections, and type aliases. An unguarded recursive alias can
therefore revisit the same classification:
```python
class Descriptor:
def __set__(self, instance: object, value: object) -> None: ...
type NonData = int | NonDataTail
type NonDataTail = NonData
type Data = Descriptor | DataTail
type DataTail = Data
```
We now evaluate both descriptor classifiers as Salsa queries and route
alias expansion back through those queries. Definite classifications use
`true`, the identity for their all-of union folds, as cycle recovery;
possible-data classification uses `false`, the identity for its any-of
fold.
The regression test exercises `is_data_descriptor`,
`may_be_data_descriptor`, and `is_definitely_non_data_descriptor` for
recursive aliases with and without a reachable data descriptor.
