checkconfig: fix plugin name in verifyLabelPlugin

Name of the plugin in the message was wrong, fix it. Export the plugin
name for that purpose.

prow/cmd/checkconfig/main.go

@@ -59,6 +59,7 @@ import (
 	"k8s.io/test-infra/prow/plugins/bugzilla"
 	"k8s.io/test-infra/prow/plugins/cherrypickunapproved"
 	"k8s.io/test-infra/prow/plugins/hold"
+	labelplugin "k8s.io/test-infra/prow/plugins/label"
 	"k8s.io/test-infra/prow/plugins/lgtm"
 	ownerslabel "k8s.io/test-infra/prow/plugins/owners-label"
 	"k8s.io/test-infra/prow/plugins/releasenote"
@@ -1064,7 +1065,7 @@ func verifyLabelPlugin(label plugins.Label) error {
 	if len(orgRepos) > 0 {
 		sort.Strings(orgRepos)
 		return fmt.Errorf("the following orgs or repos have configuration of %s plugin using the empty string as label name in restricted labels: %s",
-			verifyowners.PluginName, strings.Join(orgRepos, ", "),
+			labelplugin.PluginName, strings.Join(orgRepos, ", "),
 		)
 	}
 	return nil

prow/plugins/label/label.go

@@ -31,7 +31,9 @@ import (
 	"k8s.io/test-infra/prow/plugins"
 )
 
-const pluginName = "label"
+const (
+	PluginName = "label"
+)
 
 var (
 	defaultLabels          = []string{"kind", "priority", "area"}
@@ -43,7 +45,7 @@ var (
 )
 
 func init() {
-	plugins.RegisterGenericCommentHandler(pluginName, handleGenericComment, helpProvider)
+	plugins.RegisterGenericCommentHandler(PluginName, handleGenericComment, helpProvider)
 }
 
 func configString(labels []string) string {
@@ -64,7 +66,7 @@ func helpProvider(config *plugins.Configuration, _ []config.OrgRepo) (*pluginhel
 		},
 	})
 	if err != nil {
-		logrus.WithError(err).Warnf("cannot generate comments for %s plugin", pluginName)
+		logrus.WithError(err).Warnf("cannot generate comments for %s plugin", PluginName)
 	}
 	pluginHelp := &pluginhelp.PluginHelp{
 		Description: "The label plugin provides commands that add or remove certain types of labels. Labels of the following types can be manipulated: 'area/*', 'committee/*', 'kind/*', 'language/*', 'priority/*', 'sig/*', 'triage/*', and 'wg/*'. More labels can be configured to be used via the /label command.",