We would like to start generating the buildinstall phase using the safer
Koji Pungi Buildinstall plugin and stop the direct use of Runroot plugin.
The plugin so far exists only as PR for Koji:
https://pagure.io/koji/pull-request/1939
This commit adds support for this plugin when `lorax_use_koji_plugin`
is set to `True`.
Signed-off-by: Jan Kaluza <jkaluza@redhat.com>