The documentations for some EntityFrameworkQueryableExtensions methods are not accurate

Related to:
https://github.com/dotnet/efcore/issues/24307
The documentation now says
```C#
/// contains no elements.
```
But an exception would only be thrown for `MaxAsync` for example if the selector does not return a nullable property, if it does, EF would return null instead of throwing.

https://github.com/dotnet/efcore/blob/7318c4b5f83a08af2d903853a833475436358953/src/EFCore/Extensions/EntityFrameworkQueryableExtensions.cs#L948-L958

We might want to make these clearer.