Remove opening in new tab

[MAILPOET-1590]

lib/Util/Notices/DiscountsAnnouncement.php

@@ -30,7 +30,7 @@ class DiscountsAnnouncement {
           <p>Our annual sale is a good opportunity to get more detailed stats & great email deliverability. Don’t miss out!</p>
         [link]Visit the MailPoet Premium page[/link]', 'mailpoet'),
       'admin.php?page=mailpoet-premium',
-      array('target' => '_blank', 'class' => 'button button-primary')
+      array('class' => 'button button-primary')
     );
     $message .= '<script>jQuery(function($) {$(document).on("click", ".mailpoet-dismissible-notice .notice-dismiss",function dismiss() {const type = $(this).closest(".mailpoet-dismissible-notice").data("notice");$.ajax(window.ajaxurl,{type: "POST",data: {action: "dismissed_notice_handler",type,}});});});</script>';