switch to percona packages instead of using our custom mysql packages

[Alex Schultz]

As part of some work for 7.0, the ability to consume percona packages instead of our custom mysql packages was added into fuel-library. In order to align with consuming more upstream resources, we should test out running the percona packages at scale to see if it is a viable alternative.

https://review.openstack.org/#/c/188454/

As part of the previous change we can consume the Ubuntu provided Percona packages or we can consume the Percona provided packages.

[Vladimir Kuklin (vkuklin)]

It is not the best option to go with percona packages or with ubuntu ones. Percona is half-proprietary and ubuntu may be outdated. the best option here is to build latest stable version of mariadb+wsrep plugin + galera.

[Bartłomiej Piotrowski (bpiotrowski)]

I fail to see how Percona is more proprietary than MySQL we're currently using. Regardless of what we're going to use, let's avoid repackaging everything we can, we should try to stick to upstream.