Remove duplicated user info from pulse applabel (#521)

Given that we now have to connect via a defined user account with Mozilla Pulse there is no need anymore to keep the automation email address with us. Lets get it removed from the applabel. This will change the queue entries in Pulse guardian:

> - queue/mozauto/qa-auto@mozilla.com|mozmill_daily|mm-ci-staging.qa.scl3.mozilla.com
> + queue/mozauto/mm-ci-staging.qa.scl3.mozilla.com/mozmill_daily