json: clarify magic 100 constant

This addresses review feedback from
kubernetes#108995 (comment).

staging/src/k8s.io/component-base/logs/json/klog_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"go.uber.org/zap/zapcore"
 
+	"k8s.io/component-base/config"
 	"k8s.io/klog/v2"
 )
 
@@ -239,7 +240,9 @@ func TestKlogIntegration(t *testing.T) {
 		t.Run(tc.name, func(t *testing.T) {
 			var buffer bytes.Buffer
 			writer := zapcore.AddSync(&buffer)
-			logger, _ := NewJSONLogger(100, writer, nil, nil)
+			// This level is high enough to enable all log messages from this test.
+			verbosityLevel := config.VerbosityLevel(100)
+			logger, _ := NewJSONLogger(verbosityLevel, writer, nil, nil)
 			klog.SetLogger(logger)
 			defer klog.ClearLogger()