"marginal" plot of OptimInstanceSingleCrit axis labels & alignment, superfluous legends

[mb706]

default autoplot() (type "marginal") of a TuningInstance currently looks like this:

The legends are duplicated, and the axis labels are not really necessary since they all display the same unit. In many cases, one would probably even want the y axis to be aligned (so they all have the same range)

[mb706]

proposal imagine this is not black and white and one legend is still present...)

idk if this works when there are more coordinates being tuned over, maybe have multiple lines, each with the first row having axis labels?