cmd/appdash: make --sample-data random and generate 60 traces total.
cmd/appdash: make --sample-data random and generate 60 traces total.

60 traces is chosen as it is exactly 3 times the size of the fakeHosts
slice, to produce good results for testing an aggregated data view, in
which there are many traces with the same exact name that we are
aggregating.

bg451/appdash,joeshaw/appdash,joeshaw/appdash,bg451/appdash,bg451/appdash,joeshaw/appdash