automation: add a job to import qemu-system-aarch64 into the pipeline

automation: add a job to import qemu-system-aarch64 into the pipeline

In order to use the pre-built test-artifacts/qemu-system-aarch64 binary
for our tests, first we need to import it into the pipeline. Let's do
that the same way we did it for the kernel and Alpine Linux filesystem:
by creating a special job for it.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com>
Acked-by: Wei Liu <wl@xen.org>