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.
TEST-67-INTEGRITY times out quite often, and when it passes
it does so a few seconds short of the timeout. It's a slow
qemu test, so bump the timeout.
TEST-50-DISSECT has been reported to fail in the same way
on Debian's infrastructure, again narrowly failing or passing
just short of the timeout.
