Make the monthly querypages updates not hit each cluster on the same day

And on the 17th day he rested. Right?

Now that each page is updated every month (as opposed to just one page),
it no longer makes sense to run all updates (previously only one) for
each cluster on the same day: instead do one page per day on all clusters
at the same time.

Bug: 15434
Change-Id: Ib4c84101c7f04e8b0a96f4c05891f4d1b40154be