Make sure that the health checks handle the state transitions properly

- nodes with states Provisioning, Provisioning Fail, Deprovisioning,
  and Deprovisioning Fail should bypass health checks and should never
  transition due to the existing machinery
- nodes with states Unavailable and Installed can transition to Ready
  if they check out as healthy
- nodes in the Ready state should transition to Unavailable if they
  fail a check

awx/api/views/__init__.py

@@ -441,6 +441,7 @@ class InstanceHealthCheck(GenericAPIView):
     def post(self, request, *args, **kwargs):
         obj = self.get_object()
 
+        # Note: hop nodes are already excluded by the get_queryset method
         if obj.node_type == 'execution':
             from awx.main.tasks.system import execution_node_health_check