`juju bootstrap --add-model` results in a broken model

[Jack Shaw]

Reproduced on Juju 4.0, lxd provider

Running:
`juju bootstrap lxd lxd --add-model m`

Results in a broken model

```
$ juju status -m m
(hangs forever)
```

Whereas
```
$ juju status -m controller
$ juju models
$ juju add-model m2
$ juju status -m m2
```

All succeed

[Jack Shaw (jack-shaw)]

In controller logs I see:

```
machine-0: 12:09:34 DEBUG juju.worker.apicaller [19a84c] failed to connect
machine-0: 12:09:34 DEBUG juju.worker.dependency "api-caller" manifold worker stopped: [19a84c] "machine-0" cannot open api: unable to connect to API: dial tcp 127.0.0.1:17070: connect: connection refused
stack trace:
dial tcp 127.0.0.1:17070: connect: connection refused
github.com/juju/juju/api.gorillaDialWebsocket:672:
github.com/juju/juju/api.dialer.dial1:1092:
github.com/juju/juju/api.dialer.dial:1067: unable to connect to API
github.com/juju/juju/api.dialWebsocketMulti:963:
github.com/juju/juju/api.dialAPI:621:
github.com/juju/juju/api.Open:120:
github.com/juju/juju/internal/worker/apicaller.connectFallback:162:
github.com/juju/juju/internal/worker/apicaller.ScaryConnect:217:
github.com/juju/juju/cmd/jujud-controller/agent/machine.commonManifolds.Manifold.ManifoldConfig.startFunc.func44:99: [19a84c] "machine-0" cannot open api
machine-0: 12:09:34 ERROR juju.worker.dependency "api-caller" manifold worker returned unexpected error: [19a84c] "machine-0" cannot open api: unable to connect to API: dial tcp 127.0.0.1:17070: connect: connection refused
```

Which may (or may not) be relevant

[Thomas Miller (tlmiller)]

We need to discuss this one a little more. We haven't wired up initial model support yet as we were waiting to see if this should get moved to the bootstrap worker. If no we should be able to do this in the bootstrap agent code.