goldendataset: fix histogram metric BucketCounts length (open-telemet…

…ry#35610)

Correct Histograms as [described in
OTLP](https://github.com/open-telemetry/opentelemetry-proto/blob/main/opentelemetry/proto/metrics/v1/metrics.proto#L461)

Link to tracking Issue: Fixes
open-telemetry#35594

Testing: Tests passed

internal/coreinternal/goldendataset/metrics_gen.go

@@ -176,7 +176,7 @@ func populateDoubleHistogram(cfg MetricsCfg, dh pmetric.Histogram) {
 }
 
 func setDoubleHistogramBounds(hdp pmetric.HistogramDataPoint, bounds ...float64) {
-	counts := make([]uint64, len(bounds))
+	counts := make([]uint64, len(bounds)+1)
 	hdp.BucketCounts().FromRaw(counts)
 	hdp.ExplicitBounds().FromRaw(bounds)
 }

internal/coreinternal/goldendataset/metrics_gen_test.go

@@ -49,7 +49,7 @@ func TestDoubleHistogramFunctions(t *testing.T) {
 	pt := pmetric.NewHistogramDataPoint()
 	setDoubleHistogramBounds(pt, 1, 2, 3, 4, 5)
 	require.Equal(t, 5, pt.ExplicitBounds().Len())
-	require.Equal(t, 5, pt.BucketCounts().Len())
+	require.Equal(t, 6, pt.BucketCounts().Len())
 
 	addDoubleHistogramVal(pt, 1)
 	require.EqualValues(t, 1, pt.Count())
@@ -75,7 +75,7 @@ func TestGenDoubleHistogram(t *testing.T) {
 	pts := getMetric(md).Histogram().DataPoints()
 	pt := pts.At(0)
 	buckets := pt.BucketCounts()
-	require.Equal(t, 5, buckets.Len())
+	require.Equal(t, 6, buckets.Len())
 	require.EqualValues(t, 2, buckets.At(2))
 }