The implementation of vtkChartXY::RecalculatePlotBounds() works with
either the scaled or unscaled bounds, depending on whether scaling is
enabled on the axis. However, the logic for handling the
AdjustLowerBoundForLogPlot flag was not correctly handling the case
where the bounds were log scaled.

To address this issue, the implementation now uses some logic to
determine whether log scaling is enabled and adjusts the bounds of the
plot accordingly.

Added a test for this feature as well.