Remove redundant property

[MAILPOET-2439]

lib/Cron/Workers/StatsNotifications/NewsletterLinkRepository.php

@@ -19,7 +19,7 @@ class NewsletterLinkRepository extends Repository {
       ->createQueryBuilder('nl')
       ->join('nl.clicks', 'c')
       ->addSelect('COUNT(c.id) AS HIDDEN counter')
-      ->where('nl.newsletter_id = :newsletterId')
+      ->where('nl.newsletter = :newsletterId')
       ->setParameter('newsletterId', $newsletter_id)
       ->groupBy('nl.id')
       ->orderBy('counter', 'desc')

lib/Entities/NewsletterLinkEntity.php

@@ -18,12 +18,6 @@ class NewsletterLinkEntity {
   use CreatedAtTrait;
   use UpdatedAtTrait;
 
-  /**
-   * @ORM\Column(type="integer")
-   * @var integer
-   */
-  private $newsletter_id;
-
   /**
    * @ORM\OneToOne(targetEntity="MailPoet\Entities\NewsletterEntity")
    * @ORM\JoinColumn(name="newsletter_id", referencedColumnName="id")