use this instead of Drupal::

modules/islandora_image/src/Plugin/Action/GenerateImageDerivativeFile.php

@@ -25,7 +25,7 @@ class GenerateImageDerivativeFile extends AbstractGenerateDerivativeMediaFile {
     $config['mimetype'] = 'application/xml';
     $config['queue'] = 'islandora-connector-houdini';
     $config['destination_media_type'] = 'file';
-    $config['scheme'] = \Drupal::config('system.file')->get('default_scheme');
+    $config['scheme'] = $this->config('system.file')->get('default_scheme');
     return $config;
   }
 

modules/islandora_text_extraction/src/Plugin/Action/GenerateOCRDerivativeFile.php

@@ -27,7 +27,7 @@ class GenerateOCRDerivativeFile extends AbstractGenerateDerivativeMediaFile {
     $config['mimetype'] = 'application/xml';
     $config['queue'] = 'islandora-connector-ocr';
     $config['destination_media_type'] = 'file';
-    $config['scheme'] = \Drupal::config('system.file')->get('default_scheme');
+    $config['scheme'] = $this->config('system.file')->get('default_scheme');
     $config['destination_text_field_name'] = '';
     return $config;
   }

src/Plugin/Action/AbstractGenerateDerivative.php

@@ -141,7 +141,7 @@ class AbstractGenerateDerivative extends EmitEvent {
       'mimetype' => '',
       'args' => '',
       'destination_media_type' => '',
-      'scheme' => \Drupal::config('system.file')->get('default_scheme'),
+      'scheme' => $this->config->get('default_scheme'),
       'path' => '[date:custom:Y]-[date:custom:m]/[node:nid].bin',
     ];
   }