chore: remove DrushBatchContext

Closes #3408796

src/QueueUIBatch.php

@@ -89,13 +89,13 @@ class QueueUIBatch implements QueueUIBatchInterface {
   /**
    * {@inheritdoc}
    */
-  public function step(string $queueName, &$context) {
+  public function step(string $queue_name, array &$context) {
     // Make sure every queue exists. There is no harm in trying to recreate
     // an existing queue.
-    $info = $this->queueManager->getDefinition($queueName);
-    $this->queueFactory->get($queueName)->createQueue();
-    $queue_worker = $this->queueManager->createInstance($queueName);
-    $queue = $this->queueFactory->get($queueName);
+    $info = $this->queueManager->getDefinition($queue_name);
+    $this->queueFactory->get($queue_name)->createQueue();
+    $queue_worker = $this->queueManager->createInstance($queue_name);
+    $queue = $this->queueFactory->get($queue_name);
 
     $num_of_items = $queue->numberOfItems();
     if (!array_key_exists('num_of_total_items', $context['sandbox'])