Fix missing t()

Closes #3396590

src/Form/ABTestForm.php

@@ -118,7 +118,7 @@ class ABTestForm extends FormBase {
 
     $form['name'] = [
       '#type' => 'textfield',
-      '#title' => 'Test name',
+      '#title' => $this->t('Test name'),
       '#default_value' => empty($test['name']) ? NULL : $test['name'],
       '#size' => 65,
       '#maxlength' => 64,