ci: Fix weird filesystem globs appearing in failed test .qpa files.

When you get a filure and go looking in the results, you'll find weird stuff like this in the XML:

Reference images fill undefined pixels with 3x3 grid pattern. Attachment 0 (p' = p bin boot builds dEQP-VK.renderpass.suballocation.attachment_allocation.grow_shrink.89.qpa deqp dev etc home init install lib media mnt proc results root run sbin set-job-env-vars.sh sys tmp usr var (1, 1, 1, 1) + (-1, -1, -1, 1))

because we were not quoting the line and 'p *' was getting expanded.