Remove unused imports in the code base

Don't believe everything PhpStorm tells you, the removed trait is in use just a few lines below:

diff --git a/modules/order/src/Form/OrderReassignForm.php b/modules/order/src/Form/OrderReassignForm.php
index a63e3c3..4989e58 100644
--- a/modules/order/src/Form/OrderReassignForm.php
+++ b/modules/order/src/Form/OrderReassignForm.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\commerce_order\Form;
 
-use Drupal\commerce_order\Form\CustomerFormTrait;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Routing\CurrentRouteMatch;

Committed the rest, thanks.