#180 - New metric for rolling 12 months active users

+ Update sql script following SQL standard

Author: dustinhuynh

classes/metric/yearly_active_users_metric.php

@@ -86,7 +86,7 @@ public function generate_metric_item(int $starttime, int $finishtime): metric_it
         $lastyear = $finishtime - (60 * 60 * 24 * 365);
         $users = $DB->count_records_select(
             'user',
-            'confirmed = 1 and (lastlogin > ? or currentlogin > ?)',
+            'confirmed = 1 AND (lastlogin > ? OR currentlogin > ?)',
             [$lastyear, $lastyear]
         );
         return new metric_item($this->get_name(), $finishtime, $users, $this);