Rework prevent destroy if provider completed (#1422)

Adjust handling to use a method reference instead of attempting to
update the env value as that only appears to be available to actions
further down the chain and any changes are not visible during recovery
when exercised for real.

By passing a function reference can limit the actions that can be taken
to only allow a single call that will set a flag internal to the clean
up action.

Fixes: #1328

spec/unit/action/cleanup_on_failure_spec.rb

@@ -40,6 +40,7 @@ describe VagrantPlugins::ProviderLibvirt::Action::CleanupOnFailure do
     allow(machine).to receive(:state).and_return(state)
 
     allow(logger).to receive(:info)
+    allow(logger).to receive(:debug)
     allow(logger).to receive(:error)
 
     allow(runner).to receive(:run).and_call_original
@@ -120,7 +121,7 @@ describe VagrantPlugins::ProviderLibvirt::Action::CleanupOnFailure do
         it 'should not perform halt or destroy' do
           expect(VagrantPlugins::ProviderLibvirt::Action).to_not receive(:action_halt)
           expect(VagrantPlugins::ProviderLibvirt::Action).to_not receive(:action_destroy)
-          expect(logger).to receive(:info).with('VM completed provider setup, no need to teardown')
+          expect(logger).to receive(:debug).with('VM provider setup was completed, no need to halt/destroy')
 
           expect { runner.run(action_chain) }.to raise_error(Exception, "some action failed")
         end