MC-35985: Enable new consumer configuration settings on current consumers

Author: adifucan

app/code/Magento/MessageQueue/Model/Cron/ConsumersRunner.php

@@ -176,7 +176,11 @@ private function canBeRun(ConsumerConfigItemInterface $consumerConfig, array $al
             return false;
         }
 
-        if ($consumerConfig->getOnlySpawnWhenMessageAvailable()) {
+        $onlySpawnWhenMessageAvailable = (bool)$this->deploymentConfig->get(
+            'queue/only_spawn_when_message_available',
+            0
+        );
+        if ($onlySpawnWhenMessageAvailable || $consumerConfig->getOnlySpawnWhenMessageAvailable()) {
             try {
                 return $this->checkIsAvailableMessages->execute(
                     $connectionName,