AddOpen code fix doesn't fix FS0043 anymore

Repro:

https://github.com/dotnet/fsharp/assets/5451366/ddb423f8-e63e-42e4-b8a1-1ed9308a23da

Code:

```fsharp
module M =
    let (++) x y = 10 * x + y

module N = 
    let theAnswer = 4 ++ 2
```

AFAIU this is supposed to work: https://github.com/dotnet/fsharp/pull/2474
Currently this should be triggered by FS0043 but the fix doesn't pop up.