The first few commits are copied from libinput's CI - these are misc cleanups by @bentiss in preparation for b2c replacing qemu.
Updating the Ubuntus means we no longer fail because the apt sources are dodo.
Updating the ci-templates means we no longer fail debian sid because of a missing /etc/apt/sources.list file.
And the valgrind hack in autotools was removed because Arch fails to run valgrind atm, I don't have the time to investigate that particular issue so let's just rip it out and rely on meson's explicit valgrind runs instead.