ci/bare-metal: Use the deqp-runner bits straight out of the artifacts.

ci/bare-metal: Use the deqp-runner bits straight out of the artifacts.

We've already uploaded and downloaded them from fd.o and put them in the
rootfs, so we can clean up the extra prep work.

Our test job now extends from .test so that the artifacts' install dir
with all the scripts is extracted.  This required moving the dependency on
meson-testing to the x86 test-gl/test-vk job blocks.

Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5393>