Revert Id39d4457a: Remove experiment code for moduleStorage

Because of a bug affecting the production cluster during the initial run of the
experiment, we need to rerun it. This patch reverts Id39d4457a, restoring the
experiment setup code. As before, it will be removed at the conclusion of the
experiment.

Change-Id: Ifa97d36d3af589ca0586baad2702fb7b58b246e5
(cherry picked from commit fb192de553b995be48e570b50c6bb90113c6a821)
Merge "Revert Id39d4457a: Remove experiment code for moduleStorage" into wmf/1.23wmf9