Fix goldenfile ouput (kubernetes-retired#2366)

* Fix update-golde-files target

* Ensure golden file -update flag is defined during CI

Makefile

@@ -224,6 +224,8 @@ verify: .init verify-generated verify-client-gen verify-docs verify-vendor
 	@$(DOCKER_CMD) build/verify-errexit.sh
 	@echo Running tag verification:
 	@$(DOCKER_CMD) build/verify-tags.sh
+	@echo Validating golden file flag is defined:
+	@$(DOCKER_CMD) go test -run DRYRUN ./cmd/svcat/... -update || printf "\n\nmake test-update-goldenfiles is broken. For each failed package above, add the following empty import to one of the test files to define the -update flag:\n_ \"github.com/kubernetes-incubator/service-catalog/internal/test\""
 
 verify-docs: .init
 	@echo Running href checker$(SKIP_COMMENT):

cmd/svcat/class/get_cmd_test.go

@@ -35,6 +35,8 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	k8sfake "k8s.io/client-go/kubernetes/fake"
 	k8stesting "k8s.io/client-go/testing"
+
+	_ "github.com/kubernetes-incubator/service-catalog/internal/test"
 )
 
 func TestListClasses(t *testing.T) {

cmd/svcat/plan/get_cmd_test.go

@@ -35,6 +35,8 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	k8sfake "k8s.io/client-go/kubernetes/fake"
 	k8stesting "k8s.io/client-go/testing"
+
+	_ "github.com/kubernetes-incubator/service-catalog/internal/test"
 )
 
 func TestListPlans(t *testing.T) {