fix: simplify literal boolean checks

Author: DanielRuf

app/code/Magento/AdminNotification/Model/System/Message/Media/Synchronization/Error.php

@@ -27,7 +27,7 @@ class Error extends \Magento\AdminNotification\Model\System\Message\Media\Abstra
     protected function _shouldBeDisplayed()
     {
         $data = $this->_syncFlag->getFlagData();
-        return isset($data['has_errors']) && true == $data['has_errors'];
+        return !empty($data['has_errors']);
     }
 
     /**

app/code/Magento/AdminNotification/Model/System/Message/Media/Synchronization/Success.php

@@ -27,8 +27,8 @@ protected function _shouldBeDisplayed()
     {
         $state = $this->_syncFlag->getState();
         $data = $this->_syncFlag->getFlagData();
-        $hasErrors = isset($data['has_errors']) && true == $data['has_errors'] ? true : false;
-        return false == $hasErrors && \Magento\MediaStorage\Model\File\Storage\Flag::STATE_FINISHED == $state;
+        $hasErrors = !empty($data['has_errors']);
+        return !$hasErrors && \Magento\MediaStorage\Model\File\Storage\Flag::STATE_FINISHED == $state;
     }
 
     /**