[Glance] Deprecation and removal of sheepdog store

Hola,

Due to the stopped development and maintenance of sheepdog [0] we made the call to deprecate the store driver for removal. As the sheepdog job has not been working and there has been no interest to fix it and sheepdog upstream development has dried out as well, we are looking to remove the Glance driver for it at early U.

This means that if there is someone who is using the sheepdog store for images, Train will be the last release to fix the driver and fork it for your own repo for your own maintenance. We are also looking into killing the failing test job for the same reason [1]

[0] http://lists.wpkg.org/pipermail/sheepdog/2019-March/068451.html [1] https://review.opendev.org/#/c/660450/

Best, Erno "jokke" Kuvaja