Remove timeoutAt fallback from Job base class. The field was removed …

…over 2 years ago in 1e9a2ea and is no longer referenced anywhere else. (#43749)

src/Illuminate/Queue/Jobs/Job.php

@@ -302,7 +302,7 @@ public function timeout()
      */
     public function retryUntil()
     {
-        return $this->payload()['retryUntil'] ?? $this->payload()['timeoutAt'] ?? null;
+        return $this->payload()['retryUntil'] ?? null;
     }
 
     /**