tests: avoid implicitly asserting clean shutdown
tests: avoid implicitly asserting clean shutdown

The assertion here is causing many spurious failures that aren't
actually relevant to the test itself.

We are tracking the cause for this failure independently, and it would
make more sense to have a dedicated test for clean shutdown.

burdandrei/nomad,burdandrei/nomad,dvusboy/nomad,hashicorp/nomad,burdandrei/nomad,burdandrei/nomad,hashicorp/nomad,hashicorp/nomad,dvusboy/nomad,hashicorp/nomad,burdandrei/nomad,dvusboy/nomad,dvusboy/nomad,dvusboy/nomad,hashicorp/nomad,burdandrei/nomad,dvusboy/nomad,dvusboy/nomad,hashicorp/nomad,burdandrei/nomad