test: add t.Helper() calls to test helper functions (#7351)

plugin/test/file.go

@@ -21,6 +21,7 @@ func TempFile(dir, content string) (string, func(), error) {
 
 // WritePEMFiles creates a tmp dir with ca.pem, cert.pem, and key.pem
 func WritePEMFiles(t *testing.T) (string, error) {
+	t.Helper()
 	tempDir := t.TempDir()
 
 	data := `-----BEGIN CERTIFICATE-----

plugin/test/file_test.go

@@ -1,6 +1,8 @@
 package test
 
-import "testing"
+import (
+	"testing"
+)
 
 func TestTempFile(t *testing.T) {
 	_, f, e := TempFile(".", "test")