Remove a statsd duration anomaly sanity check.

The logic previously assumed that each bucket can only contain a
duration up to the bucket size, but this is not true for the max
sparse aggregation type. Instead of trying to keep this logic up to
date on the client, we will remove this check.

Test: Test that statsd still builds and unit-tests pass.
Change-Id: I576d75f8697b4e691b864f12ccaa6fa4611336c5