Fix EZP-21465: Cleanup extra lines in the ezurl_object_link table

Link: https://jira.ez.no/browse/EZP-21465

# Description
Stale links were created when using non translatable URLs in ezurl_object_link
Example of corrupted data (first line needs to be deleted): 

contentobject_attribute_id|contentobject_attribute_version|url_id
-------------------------------------|----------------------------------------------|-------
780|8|62
781|8|63
780|8|63

# Tests
Manual test on mysql et pgsql

Thanks to @patrickallaert for this version of the mysql script, mine was working but was not as pretty :)