Description of change
When removing manual machines, we stop the jujud agent on the machine but do not clean up or remove any Juju files. And for controllers, we retain mongo etc. We will add a separate command juju clean-juju to do the cleanup explicitly.
QA steps
bootstrap manual controller add manual machine juju remove-machine ssh into the machine and see that jujud has stopped but /var/lib/juju still there juju destroy-controller ssh into the machine and see that jujud has stopped but /var/lib/juju still there
该提问来源于开源项目：juju/juju
