[Tax] add FK to tax/sales_order_tax again (OpenMage#4334)

* add FK to tax/sales_order_tax again

* ~ fix codestyle

* Update upgrade-1.6.0.4-1.6.0.5.php

Use purge option

Author: Hanmac

app/code/core/Mage/Tax/etc/config.xml

@@ -17,7 +17,7 @@
 <config>
     <modules>
         <Mage_Tax>
-            <version>1.6.0.4</version>
+            <version>1.6.0.5</version>
         </Mage_Tax>
     </modules>
     <global>

app/code/core/Mage/Tax/sql/tax_setup/upgrade-1.6.0.4-1.6.0.5.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * OpenMage
+ *
+ * This source file is subject to the Open Software License (OSL 3.0)
+ * that is bundled with this package in the file LICENSE.txt.
+ * It is also available at https://opensource.org/license/osl-3-0-php
+ *
+ * @category   Mage
+ * @package    Mage_Tax
+ * @copyright  Copyright (c) 2006-2020 Magento, Inc. (https://www.magento.com)
+ * @copyright  Copyright (c) 2020-2025 The OpenMage Contributors (https://www.openmage.org)
+ * @license    https://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
+ */
+
+/** @var Mage_Tax_Model_Resource_Setup $this */
+
+$this->startSetup();
+
+$taxTable = $this->getTable('tax/sales_order_tax');
+$orderTable = $this->getTable('sales/order');
+
+// adds FK_SALES_ORDER_TAX_ORDER back again
+$this->getConnection()->addForeignKey(
+    $this->getFkName($taxTable, 'order_id', $orderTable, 'entity_id'),
+    $taxTable,
+    'order_id',
+    $orderTable,
+    'entity_id',
+    Varien_Db_Adapter_Interface::FK_ACTION_CASCADE,
+    Varien_Db_Adapter_Interface::FK_ACTION_CASCADE,
+    true
+);
+
+$this->endSetup();