Increase the number of Parsoid job runners

The Parsoid service can process more requests and the job queue has been
backing up a bit recently, so increase the number of runners per job slightly
from 2 to 3 (or 50% in case procs_per_iobound_type is not actually 1 as
defined in jobrunner.pp).

Change-Id: If9f86c01eecdac676e6c14e8c8c12f10d25c2d33
Merge "Increase the number of Parsoid job runners" into production