Update the chart content of ffapi-slate-test2.html to be in sync with the change of the relevant sample in firefly_client.

The content for each chart on WISE search is updated as follows,
2D scatter: w1-w2 and w2-w3 for x and y
heatmap: 3 sets, w1 vs. w2, w1 vs. w3, and w1 vs. w34.
histogram: 2 sets, w1, w2.
3D scatter: w1, w2, w3 for x, y, z.