gitlab: add fine grained job deps for all build jobs

This allows the build jobs to start running as soon as their respective
container image is ready, instead of waiting for all container builds
to finish.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210216132954.295906-3-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>