rebase: bump github.com/prometheus/client_golang from 1.15.1 to 1.16.0

Bumps [github.com/prometheus/client_golang](https://github.com/prometheus/client_golang) from 1.15.1 to 1.16.0.
- [Release notes](https://github.com/prometheus/client_golang/releases)
- [Changelog](https://github.com/prometheus/client_golang/blob/main/CHANGELOG.md)
- [Commits](https://github.com/prometheus/client_golang/compare/v1.15.1...v1.16.0)

---
updated-dependencies:
- dependency-name: github.com/prometheus/client_golang
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/github.com/prometheus/client_golang/prometheus/desc.go

@@ -18,12 +18,12 @@ import (
 	"sort"
 	"strings"
 
-	"github.com/prometheus/client_golang/prometheus/internal"
-
 	"github.com/cespare/xxhash/v2"
 	dto "github.com/prometheus/client_model/go"
 	"github.com/prometheus/common/model"
 	"google.golang.org/protobuf/proto"
+
+	"github.com/prometheus/client_golang/prometheus/internal"
 )
 
 // Desc is the descriptor used by every Prometheus Metric. It is essentially

vendor/github.com/prometheus/client_golang/prometheus/histogram.go

@@ -401,7 +401,7 @@ type HistogramOpts struct {
 	// Histogram by a Prometheus server with that feature enabled (requires
 	// Prometheus v2.40+). Sparse buckets are exponential buckets covering
 	// the whole float64 range (with the exception of the “zero” bucket, see
-	// SparseBucketsZeroThreshold below). From any one bucket to the next,
+	// NativeHistogramZeroThreshold below). From any one bucket to the next,
 	// the width of the bucket grows by a constant
 	// factor. NativeHistogramBucketFactor provides an upper bound for this
 	// factor (exception see below). The smaller
@@ -432,7 +432,7 @@ type HistogramOpts struct {
 	// bucket. For best results, this should be close to a bucket
 	// boundary. This is usually the case if picking a power of two. If
 	// NativeHistogramZeroThreshold is left at zero,
-	// DefSparseBucketsZeroThreshold is used as the threshold. To configure
+	// DefNativeHistogramZeroThreshold is used as the threshold. To configure
 	// a zero bucket with an actual threshold of zero (i.e. only
 	// observations of precisely zero will go into the zero bucket), set
 	// NativeHistogramZeroThreshold to the NativeHistogramZeroThresholdZero
@@ -639,8 +639,8 @@ func (hc *histogramCounts) observe(v float64, bucket int, doSparse bool) {
 			if frac == 0.5 {
 				key--
 			}
-			div := 1 << -schema
-			key = (key + div - 1) / div
+			offset := (1 << -schema) - 1
+			key = (key + offset) >> -schema
 		}
 		if isInf {
 			key++
@@ -817,7 +817,7 @@ func (h *histogram) observe(v float64, bucket int) {
 	}
 }
 
-// limitSparsebuckets applies a strategy to limit the number of populated sparse
+// limitBuckets applies a strategy to limit the number of populated sparse
 // buckets. It's generally best effort, and there are situations where the
 // number can go higher (if even the lowest resolution isn't enough to reduce
 // the number sufficiently, or if the provided counts aren't fully updated yet

vendor/github.com/prometheus/client_golang/prometheus/promhttp/http.go

@@ -37,6 +37,7 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -47,9 +48,10 @@ import (
 )
 
 const (
-	contentTypeHeader     = "Content-Type"
-	contentEncodingHeader = "Content-Encoding"
-	acceptEncodingHeader  = "Accept-Encoding"
+	contentTypeHeader      = "Content-Type"
+	contentEncodingHeader  = "Content-Encoding"
+	acceptEncodingHeader   = "Accept-Encoding"
+	processStartTimeHeader = "Process-Start-Time-Unix"
 )
 
 var gzipPool = sync.Pool{
@@ -121,6 +123,9 @@ func HandlerForTransactional(reg prometheus.TransactionalGatherer, opts HandlerO
 	}
 
 	h := http.HandlerFunc(func(rsp http.ResponseWriter, req *http.Request) {
+		if !opts.ProcessStartTime.IsZero() {
+			rsp.Header().Set(processStartTimeHeader, strconv.FormatInt(opts.ProcessStartTime.Unix(), 10))
+		}
 		if inFlightSem != nil {
 			select {
 			case inFlightSem <- struct{}{}: // All good, carry on.
@@ -366,6 +371,14 @@ type HandlerOpts struct {
 	// (which changes the identity of the resulting series on the Prometheus
 	// server).
 	EnableOpenMetrics bool
+	// ProcessStartTime allows setting process start timevalue that will be exposed
+	// with "Process-Start-Time-Unix" response header along with the metrics
+	// payload. This allow callers to have efficient transformations to cumulative
+	// counters (e.g. OpenTelemetry) or generally _created timestamp estimation per
+	// scrape target.
+	// NOTE: This feature is experimental and not covered by OpenMetrics or Prometheus
+	// exposition format.
+	ProcessStartTime time.Time
 }
 
 // gzipAccepted returns whether the client will accept gzip-encoded content.

vendor/github.com/prometheus/client_golang/prometheus/testutil/promlint/promlint.go

@@ -287,17 +287,15 @@ func lintUnitAbbreviations(mf *dto.MetricFamily) []Problem {
 func metricUnits(m string) (unit, base string, ok bool) {
 	ss := strings.Split(m, "_")
 
-	for unit, base := range units {
-		// Also check for "no prefix".
-		for _, p := range append(unitPrefixes, "") {
-			for _, s := range ss {
-				// Attempt to explicitly match a known unit with a known prefix,
-				// as some words may look like "units" when matching suffix.
-				//
-				// As an example, "thermometers" should not match "meters", but
-				// "kilometers" should.
-				if s == p+unit {
-					return p + unit, base, true
+	for _, s := range ss {
+		if base, found := units[s]; found {
+			return s, base, true
+		}
+
+		for _, p := range unitPrefixes {
+			if strings.HasPrefix(s, p) {
+				if base, found := units[s[len(p):]]; found {
+					return s, base, true
 				}
 			}
 		}

vendor/github.com/prometheus/client_golang/prometheus/vec.go

@@ -20,6 +20,24 @@ import (
 	"github.com/prometheus/common/model"
 )
 
+var labelsPool = &sync.Pool{
+	New: func() interface{} {
+		return make(Labels)
+	},
+}
+
+func getLabelsFromPool() Labels {
+	return labelsPool.Get().(Labels)
+}
+
+func putLabelsToPool(labels Labels) {
+	for k := range labels {
+		delete(labels, k)
+	}
+
+	labelsPool.Put(labels)
+}
+
 // MetricVec is a Collector to bundle metrics of the same name that differ in
 // their label values. MetricVec is not used directly but as a building block
 // for implementations of vectors of a given metric type, like GaugeVec,
@@ -93,6 +111,8 @@ func (m *MetricVec) DeleteLabelValues(lvs ...string) bool {
 // there for pros and cons of the two methods.
 func (m *MetricVec) Delete(labels Labels) bool {
 	labels = constrainLabels(m.desc, labels)
+	defer putLabelsToPool(labels)
+
 	h, err := m.hashLabels(labels)
 	if err != nil {
 		return false
@@ -109,6 +129,8 @@ func (m *MetricVec) Delete(labels Labels) bool {
 // To match curried labels with DeletePartialMatch, it must be called on the base vector.
 func (m *MetricVec) DeletePartialMatch(labels Labels) int {
 	labels = constrainLabels(m.desc, labels)
+	defer putLabelsToPool(labels)
+
 	return m.metricMap.deleteByLabels(labels, m.curry)
 }
 
@@ -229,6 +251,8 @@ func (m *MetricVec) GetMetricWithLabelValues(lvs ...string) (Metric, error) {
 // for example GaugeVec.
 func (m *MetricVec) GetMetricWith(labels Labels) (Metric, error) {
 	labels = constrainLabels(m.desc, labels)
+	defer putLabelsToPool(labels)
+
 	h, err := m.hashLabels(labels)
 	if err != nil {
 		return nil, err
@@ -647,15 +671,16 @@ func inlineLabelValues(lvs []string, curry []curriedLabelValue) []string {
 }
 
 func constrainLabels(desc *Desc, labels Labels) Labels {
-	constrainedValues := make(Labels, len(labels))
+	constrainedLabels := getLabelsFromPool()
 	for l, v := range labels {
 		if i, ok := indexOf(l, desc.variableLabels.labelNames()); ok {
-			constrainedValues[l] = desc.variableLabels[i].Constrain(v)
-			continue
+			v = desc.variableLabels[i].Constrain(v)
 		}
-		constrainedValues[l] = v
+
+		constrainedLabels[l] = v
 	}
-	return constrainedValues
+
+	return constrainedLabels
 }
 
 func constrainLabelValues(desc *Desc, lvs []string, curry []curriedLabelValue) []string {