staging syncs mailing lists too often

While testing the mailing list archive regeneration William noticed that that his tests were reverted. A process was copying production list and archive data from production back to staging every few hours. We do not want to sync the mailing-list without also syncing Lp's knowledge of the list because this causes sync errors in the xmlrpc runner (I finally know why we see them so often in staging). The list and archive should only be synced when the db is restored.

~launchpad-pqm/lp-production-crontabs/staging/view/head:/asuka-launchpad has two script that need removing:
    mailman-sync: https://pastebin.canonical.com/45652/
    list_sync.sh: https://pastebin.canonical.com/45653/