Revert (as intended!) "[debug] Print out documentStore stats every 60 seconds."
Revert (as intended!) "[debug] Print out documentStore stats every 60 seconds."

This reverts commit 7a0d0e6e96840bbf8cc85460b16a188877ebfd12, as I intended
when I originally introduced it.

Ref: https://github.com/apollographql/apollo-server/pull/2111#issuecomment-454779949

apollostack/apollo-server