Ubuntu/Debian: Do not use mirror repository for mimic
Ubuntu/Debian: Do not use mirror repository for mimic

... because mimic is no longer hosted in the mirror repository[1].

[1] http://mirror.iad.rax.opendev.org/

Closes-Bug: #1902670
Change-Id: If7653b7991387116ff8a9a3ea3f038ec01a27985

openstack/puppet-openstack-integration,openstack/puppet-openstack-integration,openstack/puppet-openstack-integration