This is an addendum to #3958, which also instructs apt to ignore the "Valid Until" date in Release files inside the slave containers, making a complete solution, much like the previously abandoned PR #2609. This patch also unifies file names and contents.
When the Debian team archives a repo, it stops updating the "Valid Until" date, thus apt-get will not apply updates for that repo unless we explicitly tell it to ignore the "Valid Until" date. Also, this has become an issue with active (i.e., non-archived) repos twice in the past year because the Debian folks seem to occasionally let the expiration lapse before updating the date. This will cause SONiC builds to fail with a message like E: Release file for http://debian-archive.trafficmanager.net/debian-security/dists/jessie/updates/InRelease is expired (invalid since 3d 3h 11min 20s). Updates for this repository will not be applied. until the dates have been updated and propagated to all mirrors. With this patch, SONiC should no longer be affected by lapsed "Valid Until" dates, whether they be accidental or purposeful.
