TUN-6724: Migrate to sentry-go from raven-go

vendor/github.com/getsentry/sentry-go/traces_sampler.go

@@ -0,0 +1,19 @@
+package sentry
+
+// A SamplingContext is passed to a TracesSampler to determine a sampling
+// decision.
+//
+// TODO(tracing): possibly expand SamplingContext to include custom /
+// user-provided data.
+type SamplingContext struct {
+	Span   *Span // The current span, always non-nil.
+	Parent *Span // The parent span, may be nil.
+}
+
+// The TracesSample type is an adapter to allow the use of ordinary
+// functions as a TracesSampler.
+type TracesSampler func(ctx SamplingContext) float64
+
+func (f TracesSampler) Sample(ctx SamplingContext) float64 {
+	return f(ctx)
+}