Add a template for baseline RT checks

The maintainers want to simplify their workflow, and part of it is to run RT checks on baseline runs (after merge) to clearly identify problems so the RT team has an easier time and knows what exactly needs to be dealt with.

The regular RT check is meant to only run on merge requests and gitlab variables can't be expanded to use fallbacks until gitlab-org/gitlab-runner#1867 (closed) gets fixed.

We can either add the variable to every supported kernel gitlabci file, or add a template that has it, in case we'll need to extend the RT baseline checks we should opt for the later.

Signed-off-by: Veronika Kabatova vkabatov@redhat.com