CIs set QEMU and nspawn timeouts by themselves which reflect their needs
and possibilities, so let's respect that value, instead of using one
pre-set value which might or might not work for all of them.
Both Ubuntu CI and CentOS CI set these values themselves.
Specifying the test number manually is tedious and prone to errors (as
recently proven). Since we have all the necessary data to work out the
test number, let's do it automagically.
Frantisek Sumsal
Yu Watanabe
Zbigniew Jędrzejewski-Szmek