ENGCOM-3302: MAGE_DIRS overwrite fix in pub/index.php #18727

 - Merge Pull Request #18727 from mmenozzi/magento2:mage-dirs-overwrite-in-pub-index-fix
 - Merged commits:
   1. c34e734

Author: magento-engcom-team

pub/index.php

@@ -25,12 +25,15 @@
 }
 
 $params = $_SERVER;
-$params[Bootstrap::INIT_PARAM_FILESYSTEM_DIR_PATHS] = [
-    DirectoryList::PUB => [DirectoryList::URL_PATH => ''],
-    DirectoryList::MEDIA => [DirectoryList::URL_PATH => 'media'],
-    DirectoryList::STATIC_VIEW => [DirectoryList::URL_PATH => 'static'],
-    DirectoryList::UPLOAD => [DirectoryList::URL_PATH => 'media/upload'],
-];
+$params[Bootstrap::INIT_PARAM_FILESYSTEM_DIR_PATHS] = array_replace_recursive(
+    $params[Bootstrap::INIT_PARAM_FILESYSTEM_DIR_PATHS],
+    [
+        DirectoryList::PUB => [DirectoryList::URL_PATH => ''],
+        DirectoryList::MEDIA => [DirectoryList::URL_PATH => 'media'],
+        DirectoryList::STATIC_VIEW => [DirectoryList::URL_PATH => 'static'],
+        DirectoryList::UPLOAD => [DirectoryList::URL_PATH => 'media/upload'],
+    ]
+);
 $bootstrap = \Magento\Framework\App\Bootstrap::create(BP, $params);
 /** @var \Magento\Framework\App\Http $app */
 $app = $bootstrap->createApplication(\Magento\Framework\App\Http::class);