test: Simplify Machines test wait conditions
test: Simplify Machines test wait conditions

- Only show the names with `virsh list --name` to avoid having to deal
  with the header noise.

- Replace the expensive ssh command retry loops with shell loops.

cockpituous/cockpit,deryni/cockpit,martinpitt/cockpit,cockpituous/cockpit,deryni/cockpit,deryni/cockpit,cockpituous/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,garrett/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,mvollmer/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,garrett/cockpit,garrett/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,deryni/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,garrett/cockpit,mvollmer/cockpit,deryni/cockpit,mvollmer/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,garrett/cockpit,cockpit-project/cockpit,mvollmer/cockpit,cockpit-project/cockpit