rebase: bump google.golang.org/grpc from 1.68.1 to 1.69.0

Bumps [google.golang.org/grpc](https://github.com/grpc/grpc-go) from 1.68.1 to 1.69.0.
- [Release notes](https://github.com/grpc/grpc-go/releases)
- [Commits](https://github.com/grpc/grpc-go/compare/v1.68.1...v1.69.0)

---
updated-dependencies:
- dependency-name: google.golang.org/grpc
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

vendor/google.golang.org/grpc/experimental/stats/metrics.go

@@ -19,8 +19,6 @@
 // Package stats contains experimental metrics/stats API's.
 package stats
 
-import "maps"
-
 // MetricsRecorder records on metrics derived from metric registry.
 type MetricsRecorder interface {
 	// RecordInt64Count records the measurement alongside labels on the int
@@ -39,76 +37,3 @@ type MetricsRecorder interface {
 	// gauge associated with the provided handle.
 	RecordInt64Gauge(handle *Int64GaugeHandle, incr int64, labels ...string)
 }
-
-// Metric is an identifier for a metric.
-type Metric string
-
-// Metrics is a set of metrics to record. Once created, Metrics is immutable,
-// however Add and Remove can make copies with specific metrics added or
-// removed, respectively.
-//
-// Do not construct directly; use NewMetrics instead.
-type Metrics struct {
-	// metrics are the set of metrics to initialize.
-	metrics map[Metric]bool
-}
-
-// NewMetrics returns a Metrics containing Metrics.
-func NewMetrics(metrics ...Metric) *Metrics {
-	newMetrics := make(map[Metric]bool)
-	for _, metric := range metrics {
-		newMetrics[metric] = true
-	}
-	return &Metrics{
-		metrics: newMetrics,
-	}
-}
-
-// Metrics returns the metrics set. The returned map is read-only and must not
-// be modified.
-func (m *Metrics) Metrics() map[Metric]bool {
-	return m.metrics
-}
-
-// Add adds the metrics to the metrics set and returns a new copy with the
-// additional metrics.
-func (m *Metrics) Add(metrics ...Metric) *Metrics {
-	newMetrics := make(map[Metric]bool)
-	for metric := range m.metrics {
-		newMetrics[metric] = true
-	}
-
-	for _, metric := range metrics {
-		newMetrics[metric] = true
-	}
-	return &Metrics{
-		metrics: newMetrics,
-	}
-}
-
-// Join joins the metrics passed in with the metrics set, and returns a new copy
-// with the merged metrics.
-func (m *Metrics) Join(metrics *Metrics) *Metrics {
-	newMetrics := make(map[Metric]bool)
-	maps.Copy(newMetrics, m.metrics)
-	maps.Copy(newMetrics, metrics.metrics)
-	return &Metrics{
-		metrics: newMetrics,
-	}
-}
-
-// Remove removes the metrics from the metrics set and returns a new copy with
-// the metrics removed.
-func (m *Metrics) Remove(metrics ...Metric) *Metrics {
-	newMetrics := make(map[Metric]bool)
-	for metric := range m.metrics {
-		newMetrics[metric] = true
-	}
-
-	for _, metric := range metrics {
-		delete(newMetrics, metric)
-	}
-	return &Metrics{
-		metrics: newMetrics,
-	}
-}