Spillover from #2861, calling RandomWalk() multiple times in rapid succession does not properly re-seed. Fix this internally using a private static instance of the random data generator.

ScottPlot.Plot plt = new();
for (int k = 0; k < 50; k++)
{
    double[] data = ScottPlot.Generate.RandomWalk(10000);
    plt.AddSignalConst(data);
}