feat(otlp): extend metric testing support

ci/fingerprints/otel_metrics/fingerprint.txt

@@ -1 +1 @@
-otel_metrics_grpc: 1a99c0f4baf2470e547d0038dcaa6e7f134a1a31ae9dea50460e21f5e4e3a562 entropy=6.7343
+otel_metrics_grpc: ae0fe4374599f61afe94c09b3a92d9689b30ea49dc9c0f1be229abf8544153a6 entropy=6.7752

lading_payload/benches/opentelemetry_metric.rs

@@ -20,6 +20,7 @@ fn opentelemetry_metric_setup(c: &mut Criterion) {
                     gauge: 50,
                     sum_delta: 25,
                     sum_cumulative: 25,
+                    ..Default::default()
                 },
                 contexts: Contexts {
                     total_contexts: ConfRange::Constant(100),
@@ -49,6 +50,7 @@ fn opentelemetry_metric_throughput(c: &mut Criterion) {
                             gauge: 50,
                             sum_delta: 25,
                             sum_cumulative: 25,
+                            ..Default::default()
                         },
                         contexts: Contexts {
                             total_contexts: ConfRange::Constant(100),

lading_payload/src/opentelemetry/common/templates.rs

@@ -96,6 +96,7 @@ where
 
     /// Check if any template in the pool can fit within the given budget.
     /// Returns true if at least one template fits, false otherwise.
+    #[cfg(test)]
     pub(crate) fn template_fits(&self, budget: usize) -> bool {
         // Check if any existing template in the pool fits
         self.by_size.range(..=budget).next().is_some()