Fix namespacing of lxd config

[voidspace]

No longer auto-prefix keys in the lxd config with the "user." namespace. This was wrong in some places and can be done manually in the one place it is needed.

Fixes bug #1631254.

To QA
The specific bug being fixed is that LXD containers would not autostart. To verify this is fixed:

• Bootstrap
• Either switch to the controller model or add a new machine so you have a machine 0)
• juju add-machine lxd:0
• juju ssh 0 sudo lxc list
• Using container-id from this: juju ssh 0 sudo lxc stop juju-CONTAINER-ID
• juju ssh 0 sudo reboot

After the reboot is completed the container should be running again, having restarted correctly.

[macgreagoir]

LGTM

Ran QA steps successfully.

sudo lxc config show juju-<id>-0-lxd-0 | grep autostart showed expected config of boot.autostart: "true" outside the previous user namespace.

[voidspace]

$$merge$$

[jujubot]

Status: merge request accepted. Url: http://juju-ci.vapour.ws:8080/job/github-merge-juju

[jujubot]

Build failed: Tests failed
build url: http://juju-ci.vapour.ws:8080/job/github-merge-juju/9942

[voidspace]

Nope, this approach is not sufficient. Bootstrapping in the following way shows up the problem:

juju --debug bootstrap --constraints mem=2G lxd/localhost merge-juju-lxd --default-model merge-juju-lxd --agent-version 2.2-alpha1 --bootstrap-series xenial

Back to the drawing board.