Check for any differences in behavior between DDSketch implementation in Saluki and Datadog Agent.

[tobz]

Context

Saluki currently uses an implementation of DDSketch based on that of the Datadog Agent (seen here, in a tangentially-related package).

While the implementation in Saluki comes from Vector, where a good amount of effort was spent trying to ensure parity with the Agent-based implementation, the logic and associated unit tests have not been re-evaluated in a long time.

We should reaffirm that Saluki's implementation is correct by double-checking what we have -- the implementation itself, the unit tests we have, etc -- with that of the Datadog Agent implementation.