.gitlab-ci.yml: kill local jobs

.gitlab-ci.yml: kill local jobs

The idea behind local jobs was that you would have jobs that
share the same setup as the citemplate ones but would always
be pointing to your forked registry with your custom build of
the image, since the citemplate hardcoded the image it was
running against.

With the changes introduced in the previous commit
we now mirror the setup from freedesktop/ci-templates and the idea
is that jobs always run from the registry in your fork. If the
image sha/id matches the one from the upstream registry, its copied
over else a new one is build, pushed and tested.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-ci/-/merge_requests/308>