non-linear box/violin hover label quirks

[alexcjohnson]

Horizontal violins have some odd hover label behavior. Labels are horizontal, not tipped as they are for horizontal boxes and bars, and (perhaps related) they're anchored to the middle of the violin, not the edge (or off the edge) as they are for vertical violins

And at least in violin_non-linear the KDE label disappears past the max point, even though the KDE line is still there.

cc @etpinard

[etpinard]

This seems to happen on non-linear axes for both violin and box traces.

Mock box_grouped_horz + Plotly.restyle(gd, 'type', 'violin') appears to work fine. Whereas violin_non-linear + Plotly.restyle(gd, 'type', 'box') also shows the problem.

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EDIT the above claim isn't true. The bugs happens on subplots with a single box or violin trace. More info in #2970 (comment)