This indicates which measurement to use if/when the service
automatically selects the final measurement from previously reported
intermediate measurements. Choose this based on two considerations:
A) Do you expect your measurements to monotonically improve? If so,
choose LAST_MEASUREMENT. On the other hand, if you're in a situation
where your system can "over-train" and you expect the performance to
get better for a while but then start declining, choose
BEST_MEASUREMENT. B) Are your measurements significantly noisy
and/or irreproducible? If so, BEST_MEASUREMENT will tend to be
over-optimistic, and it may be better to choose LAST_MEASUREMENT. If
both or neither of (A) and (B) apply, it doesn't matter which
selection type is chosen.