chore: import upstream snapshot with attribution

pkg/observability/metrics/noop_sink.go

@@ -0,0 +1,19 @@
+package metrics
+
+import "time"
+
+// NoopMetrics is a no-op implementation of the Metrics interface.
+type NoopMetrics struct{}
+
+var _ Metrics = (*NoopMetrics)(nil)
+
+// NewNoopMetrics returns a new NoopMetrics.
+func NewNoopMetrics() *NoopMetrics {
+	return &NoopMetrics{}
+}
+
+func (n *NoopMetrics) Increment(_ string, _ map[string]string)                       {}
+func (n *NoopMetrics) Counter(_ string, _ map[string]string, _ int64)                {}
+func (n *NoopMetrics) Distribution(_ string, _ map[string]string, _ float64)         {}
+func (n *NoopMetrics) DistributionMs(_ string, _ map[string]string, _ time.Duration) {}
+func (n *NoopMetrics) WithTags(_ map[string]string) Metrics                          { return n }