panic: Tried to use uncalculated class infos

`zuban check` crashes when checking this fuzzed code:

```python
@f
class C:
    C

@f
def f(C: C):
    with C:
        pass
```

```
thread 'main' panicked at crates/zuban_python/src/file/type_computation/class.rs:143:32:
Tried to use uncalculated class infos for C
```

### Version info
39635088ab