Remove NonNegativeBuckets (#781)

NonNegativeBuckets were used for our generated metrics. However, it is
in the public metrics package, and users can rely on it to define their
histograms.

However, NonNegativeBuckets has a huge number of buckets which lead to
large data for the metrics. The users have complained that our buckets are
too fine-grained and the cost to export the metrics is quite high.

This PR removes the NonNegativeBuckets and forces the user to define
their own buckets for their histograms.

Author: rgrandl

examples/reverser/reverser.go

@@ -26,7 +26,7 @@ import (
 var stringLength = metrics.NewHistogram(
 	"reverse_string_length",
 	"The length of strings passed to the Reverse method",
-	metrics.NonNegativeBuckets,
+	[]float64{1, 10, 100, 1000, 10000, 100000, 1000000},
 )
 
 // Reverser component.

metrics/buckets.go

@@ -50,15 +50,6 @@
 //		)
 //	)
 //
-// [NonNegativeBuckets] returns a default set of non-negative buckets. It is
-// useful when declaring histograms that measure things like memory or latency.
-//
-//	var exampleLatency = metrics.NewHistogram(
-//		"example_latency",
-//		"The latency of something, in microseconds",
-//		metrics.NonNegativeBuckets,
-//	)
-//
 // # Updating Metrics
 //
 // Every metric type has a set of methods you can use to update the metric.