DAR-1778 Cleanup Hubs tracking params

* changed eventname to wikiahubs ( this is what the processor is looking for
  - see https://github.com/Wikia/analytics/blob/master/lib/Wikia/DW/Event/FileParser.pm#L43 )
* removed redundant passing of content language (it's already passed)
* removed redundant fields (user name and page title)