Fixing a test for Magento Newsletter.

Author: tiagosampaio

app/code/Magento/Newsletter/Test/Unit/Model/ProblemTest.php

@@ -68,6 +68,7 @@ protected function setUp()
             ->disableOriginalConstructor()
             ->getMock();
         $this->subscriberFactoryMock = $this->getMockBuilder(SubscriberFactory::class)
+            ->disableOriginalConstructor()
             ->getMock();
         $this->subscriberMock = $this->getMockBuilder(Subscriber::class)
             ->disableOriginalConstructor()