Use Debian mirror in CI jobs
Use Debian mirror in CI jobs

There is Debian mirror on each CI worker so we should use it.

Change-Id: Id3b55ac470a977be7ee7decdef3b49e8d89a130f

stackforge/kolla,openstack/kolla,rahulunair/kolla,openstack/kolla,stackforge/kolla,rahulunair/kolla,stackforge/kolla