Always include at least one value in a DogStastD metric

This commit fixes a bug in the last release. We allowed for the creation of
DogStatsD metrics that have no values associated with them with probability
1/33. We now require at least one value and do not adjust the maximum of 32.

REF SMP-527

Signed-off-by: Brian L. Troutwine <brian.troutwine@datadoghq.com>

Author: blt

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Disallow the creation of DogStatsD metrics with no values
 
 ## [0.15.1]
 ### Added

src/payload/dogstatsd/metric.rs

@@ -27,7 +27,7 @@ impl Generator<Metric> for MetricGenerator {
         let name = self.names.choose(&mut rng).unwrap().clone();
         let tags = choose_or_not(&mut rng, &self.tags);
         let sample_rate = rng.gen();
-        let total_values = rng.gen_range(0..32);
+        let total_values = rng.gen_range(1..32);
         let value: Vec<common::NumValue> =
             Standard.sample_iter(&mut rng).take(total_values).collect();