Allow segmenting poolcounter traffic into separate queues per wiki

Right now we vary MWSearch based on pool lvs ip. This will let us
do something similar for Cirrus without having to have actual
separate lvs for each pool.

Change-Id: Iea7ebff747e053d919a9682a9a198bdbb4f7ed3c
Merge "Allow segmenting poolcounter traffic into separate queues per wiki"