What happened? (You can include a screenshot if it helps explain)

Currently no matter what value you set for iteration in the load results manually tool, it will only try to load from the iteration that is connected to the ensemble. If you have manually created a new ensemble, this is usually 0.
Reason is the following code which is used to load results from runpath, in libres_facade.py:

    def load_from_forward_model(
        self,
        ensemble: Ensemble,
        realisations: npt.NDArray[np.bool_],
        iteration: Optional[int] = None,
    ) -> int:
        if iteration is not None:
            warnings.warn(
                "The iteration argument has no effect, iteration is read from ensemble",
                DeprecationWarning,
                stacklevel=1,
            )

What did you expect to happen?

Would expect the tool to load from the iteration specified.

steps to reproduce

ert gui poly.ert
run an es_mda run
Create new experiment (and ensemble) in manage experiment
Try to load results manually into new ensemble, with iteration>0
Can see in the plotter that the result is from iteration 0

Environment where bug has been observed

• python 3.8
• python 3.9
• python 3.10
• python 3.11
• python 3.12
• macosx
• rhel7
• rhel8
• local queue
• lsf queue
• slurm queue
• openPBS queue
• used flag --enable-scheduler