Include mailman domains in local domains.
Include mailman domains in local domains.

The local hostname is included in local_domains by default,
but in case we're hosting mailman domains other than the local
hostname, include them.

Change-Id: I733b8fe8cacc2cfd2d7a0d33236ed9e2273c15da

open-switch/infra_puppet-jenkins,open-switch/infra_puppet-jenkins