The e2e test code is absolutely hideous and leaks processes and files
on disk. NomadAgent seems useful, but the clientstate e2e tests are very
messy and slow. The last test "Corrupt" is probably the most useful as
it explicitly corrupts the state file whereas the other tests attempt to
reproduce steps thought to cause corruption in earlier releases of
Nomad.
Upgrade e2e tests are failing and we haven't had bandwith to fix yet.
Having them fail makes it easy for us to miss other failures and
regressions.
As such, skip the upgrade e2e tests until we fix them.
