BAC-589: improve images popularity in ImageServing

Add a query that gets all images being redirect to an image we're getting popularity for

```mysql
mysql> explain (select /* ImageServingDriverMainNS::getImagesPopularity::redirects Macbre */ page_title, rd_title from `redirect` left join page on page_id = rd_from where rd_namespace = 6 AND rd_title = 'Jenson_Button_bahrain_2012.jpg' limit 5) UNION ALL (select page_title, rd_title from `redirect` left join page on page_id = rd_from where rd_namespace = 6 AND rd_title = 'Flag_of_the_United_Kingdom.svg' limit 5);
+----+--------------+------------+--------+---------------+-------------+---------+---------------------+------+--------------------------+
| id | select_type  | table      | type   | possible_keys | key         | key_len | ref                 | rows | Extra                    |
+----+--------------+------------+--------+---------------+-------------+---------+---------------------+------+--------------------------+
|  1 | PRIMARY      | redirect   | ref    | rd_ns_title   | rd_ns_title | 261     | const,const         |    1 | Using where; Using index |
|  1 | PRIMARY      | page       | eq_ref | PRIMARY       | PRIMARY     | 4       | f1.redirect.rd_from |    1 |                          |
|  2 | UNION        | redirect   | ref    | rd_ns_title   | rd_ns_title | 261     | const,const         |    1 | Using where; Using index |
|  2 | UNION        | page       | eq_ref | PRIMARY       | PRIMARY     | 4       | f1.redirect.rd_from |    1 |                          |
| NULL | UNION RESULT | <union1,2> | ALL    | NULL          | NULL        | NULL    | NULL                | NULL |                          |
+----+--------------+------------+--------+---------------+-------------+---------+---------------------+------+--------------------------+
5 rows in set (0.00 sec)
```

@moli - please review the SQL

Don't merge it - waiting for QA