Set up $wgParsoidWikiPrefix to $wgDBname and double Parsoid load

* Prepare to use $wgParsoidWikiPrefix instead of $wgLanguageCode to construct
  Parsoid URLs in the Parsoid PHP extension.

* Bump up the Parsoid load to 2/3 of all update jobs.

Change-Id: Ic6dcdb82808f21d6137b6dca177778e7a5979c23
Merge "Set up $wgParsoidWikiPrefix to $wgDBname and double Parsoid load"