[chore] [awsfirehosereceiver] use math/rand/v2 (open-telemetry#37465)

#### Description

Update to `math/rand/v2`.

#### Link to tracking issue

Part of
open-telemetry#34676

#### Testing

N/A

#### Documentation

N/A

receiver/awsfirehosereceiver/internal/unmarshaler/cwmetricstream/metricsbuilder_test.go

@@ -4,7 +4,7 @@
 package cwmetricstream
 
 import (
-	"math/rand"
+	"math/rand/v2"
 	"testing"
 	"time"
 
@@ -208,5 +208,5 @@ func TestResourceMetricsBuilder(t *testing.T) {
 
 // testCWMetricValue is a convenience function for creating a test cWMetricValue
 func testCWMetricValue() *cWMetricValue {
-	return &cWMetricValue{100, 0, float64(rand.Int63n(100)), float64(rand.Int63n(4))}
+	return &cWMetricValue{100, 0, float64(rand.Int64N(100)), float64(rand.Int64N(4))}
 }