Intermediate container cleanup should be done at the end

[mlandauer]

Currently it's easily possible for an intermediate container not to get cleaned up properly. Instead why don't we tag all intermediate containers with the run id and marking the type of container it is and then do the cleanup at the end. That way we can more consistently ensure that things will get properly cleaned up if the background job runs to completion.

[mlandauer]

I think when I said intermediate container I think I meant intermediate image. Hmmm....

We now don't generate intermediate images so much of this problem should automatically go away. Closing this.