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/stats/metrics.go

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2024 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package stats
+
+import "maps"
+
+// MetricSet is a set of metrics to record. Once created, MetricSet is immutable,
+// however Add and Remove can make copies with specific metrics added or
+// removed, respectively.
+//
+// Do not construct directly; use NewMetricSet instead.
+type MetricSet struct {
+	// metrics are the set of metrics to initialize.
+	metrics map[string]bool
+}
+
+// NewMetricSet returns a MetricSet containing metricNames.
+func NewMetricSet(metricNames ...string) *MetricSet {
+	newMetrics := make(map[string]bool)
+	for _, metric := range metricNames {
+		newMetrics[metric] = true
+	}
+	return &MetricSet{metrics: newMetrics}
+}
+
+// Metrics returns the metrics set. The returned map is read-only and must not
+// be modified.
+func (m *MetricSet) Metrics() map[string]bool {
+	return m.metrics
+}
+
+// Add adds the metricNames to the metrics set and returns a new copy with the
+// additional metrics.
+func (m *MetricSet) Add(metricNames ...string) *MetricSet {
+	newMetrics := make(map[string]bool)
+	for metric := range m.metrics {
+		newMetrics[metric] = true
+	}
+
+	for _, metric := range metricNames {
+		newMetrics[metric] = true
+	}
+	return &MetricSet{metrics: newMetrics}
+}
+
+// Join joins the metrics passed in with the metrics set, and returns a new copy
+// with the merged metrics.
+func (m *MetricSet) Join(metrics *MetricSet) *MetricSet {
+	newMetrics := make(map[string]bool)
+	maps.Copy(newMetrics, m.metrics)
+	maps.Copy(newMetrics, metrics.metrics)
+	return &MetricSet{metrics: newMetrics}
+}
+
+// Remove removes the metricNames from the metrics set and returns a new copy
+// with the metrics removed.
+func (m *MetricSet) Remove(metricNames ...string) *MetricSet {
+	newMetrics := make(map[string]bool)
+	for metric := range m.metrics {
+		newMetrics[metric] = true
+	}
+
+	for _, metric := range metricNames {
+		delete(newMetrics, metric)
+	}
+	return &MetricSet{metrics: newMetrics}
+}