chore(config): drop the Default impl from the histogram component config

A component config struct should take its values from the typed configuration
model, not restate defaults. Remove impl Default for HistogramConfiguration and
build the representative configuration explicitly in the tests that need one.

Author: webern

lib/saluki-components/src/transforms/aggregate/config.rs

@@ -150,25 +150,6 @@ impl HistogramConfiguration {
     }
 }
 
-impl Default for HistogramConfiguration {
-    fn default() -> Self {
-        Self {
-            statistics: vec![
-                HistogramStatistic::Maximum,
-                HistogramStatistic::Median,
-                HistogramStatistic::Average,
-                HistogramStatistic::Count,
-                HistogramStatistic::Percentile {
-                    q: 0.95,
-                    suffix: "95percentile".into(),
-                },
-            ],
-            copy_to_distribution: false,
-            copy_to_distribution_prefix: "".into(),
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

lib/saluki-components/src/transforms/aggregate/mod.rs

@@ -871,6 +871,25 @@ mod tests {
     use super::config::HistogramStatistic;
     use super::*;
 
+    /// The histogram statistics the Datadog Agent computes by default, for aggregation-state tests
+    /// that need a representative configuration.
+    fn default_hist_config() -> HistogramConfiguration {
+        HistogramConfiguration::from_statistics(
+            &[
+                HistogramStatistic::Maximum,
+                HistogramStatistic::Median,
+                HistogramStatistic::Average,
+                HistogramStatistic::Count,
+                HistogramStatistic::Percentile {
+                    q: 0.95,
+                    suffix: "95percentile".into(),
+                },
+            ],
+            false,
+            String::new(),
+        )
+    }
+
     const BUCKET_WIDTH_SECS: NonZeroU64 = NonZeroU64::new(10).expect("not zero");
     const BUCKET_WIDTH: Duration = Duration::from_secs(BUCKET_WIDTH_SECS.get());
     const COUNTER_EXPIRE_SECS: u64 = 20;
@@ -1070,7 +1089,7 @@ mod tests {
             BUCKET_WIDTH_SECS,
             2,
             COUNTER_EXPIRE,
-            HistogramConfiguration::default(),
+            default_hist_config(),
             Telemetry::noop(),
         );
 
@@ -1120,7 +1139,7 @@ mod tests {
             BUCKET_WIDTH_SECS,
             2,
             COUNTER_EXPIRE,
-            HistogramConfiguration::default(),
+            default_hist_config(),
             Telemetry::noop(),
         );
 
@@ -1175,7 +1194,7 @@ mod tests {
             BUCKET_WIDTH_SECS,
             10,
             COUNTER_EXPIRE,
-            HistogramConfiguration::default(),
+            default_hist_config(),
             Telemetry::noop(),
         );
 
@@ -1224,7 +1243,7 @@ mod tests {
             BUCKET_WIDTH_SECS,
             10,
             COUNTER_EXPIRE,
-            HistogramConfiguration::default(),
+            default_hist_config(),
             Telemetry::noop(),
         );
 
@@ -1338,7 +1357,7 @@ mod tests {
             BUCKET_WIDTH_SECS,
             10,
             COUNTER_EXPIRE,
-            HistogramConfiguration::default(),
+            default_hist_config(),
             Telemetry::noop(),
         );
 
@@ -1405,7 +1424,7 @@ mod tests {
             BUCKET_WIDTH_SECS,
             10,
             COUNTER_EXPIRE,
-            HistogramConfiguration::default(),
+            default_hist_config(),
             Telemetry::noop(),
         );
 
@@ -1462,13 +1481,7 @@ mod tests {
         let builder = MetricsBuilder::default();
         let telemetry = Telemetry::new(&builder);
 
-        let mut state = AggregationState::new(
-            BUCKET_WIDTH_SECS,
-            2,
-            COUNTER_EXPIRE,
-            HistogramConfiguration::default(),
-            telemetry,
-        );
+        let mut state = AggregationState::new(BUCKET_WIDTH_SECS, 2, COUNTER_EXPIRE, default_hist_config(), telemetry);
 
         // Make sure our telemetry is registered at default values.
         assert_eq!(recorder.gauge("aggregate_active_contexts"), Some(0.0));