gitlab-ci: Drop dependencies:

gitlab-ci: Drop dependencies:

Artifacts from jobs listed in needs: are downloaded by default, so
there's no need to list them in dependencies: as well (in fact,
https://docs.gitlab.com/ce/ci/yaml/#artifact-downloads-with-needs says
using dependencies: together with needs: is invalid, so we might have
been getting lucky...).

Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5845>