false positive helpful-string

```py
def f[T, T2](t: T, t2: T2) -> T | T2:
return t

print(f"{f("", "")}") # The string for "object" isn't helpful in a user-facing or semantic string
```

Start with the Python reproducer in the issue and locate the diagnostic that reports a non-helpful string for the nested f-string. Confirm the warning is a false positive for this user-facing or semantic string, then run the relevant checker tests and add coverage showing this example is accepted.

Written by the indexing model from the issue text.