Kolla Ubuntu gates rely on bug in Kolla to work

[Edmund Rhudy]

This bug is related to https://bugs.launchpad.net/kolla/+bug/1633187 and https://review.openstack.org/#/c/414639.

The gate jobs that test Kolla builds on Ubuntu supply a custom sources.list. Previously, due to the bug described in #1633187, this sources.list was not used. When I fixed this behavior in the PR linked above, the custom sources.list started being used, and the Ubuntu builds now fail because the OSIC mirrors are apparently unsigned.

I think that either the OSIC Ubuntu mirrors should probably be straight syncs of Canonical's mirrors, so that Canonical's signing key works with them, or the gate jobs should not use the OSIC mirrors and should use Canonical's mirrors instead (at the cost of probably more gate failures due to problems with fetching packages).

[OpenStack Infra (hudson-openstack)]

Change abandoned by Edmund Rhudy (<email address hidden>) on branch: master
Review: https://review.openstack.org/414639
Reason: abandoning this change in favor of the approach in https://review.openstack.org/#/c/419610/