Bootstrap on microk8s aborts after one failed attempt to contact API server

[Carl Csaposs]

`juju bootstrap` fails to retry if unable to connect to API server when bootstrapping microk8s

Example: https://github.com/canonical/postgresql-k8s-operator/actions/runs/9671984491/job/26683740781#step:16:20

```
$ sg 'snap_microk8s' -c "juju bootstrap 'microk8s' '--agent-version=3.1.8'"
Creating Juju controller "microk8s-localhost" on microk8s/localhost
Bootstrap to Kubernetes cluster identified as microk8s/localhost
Creating k8s resources for controller "controller-microk8s-localhost"
Downloading images
Starting controller pod
Bootstrap agent now started
Contacting Juju controller at 10.152.183.89 to verify accessibility...
ERROR unable to contact api server after 1 attempts: try was stopped
```

Full GitHub Actions log uploaded as attachment

We are unable to reproduce this issue consistently—we believe it's a transient issue that would be resolved on a retry

Context: https://matrix.to/#/!xzmWHtGpPfVCXKivIh:ubuntu.com/$hpqkTtad-vr4JBVRNye12v8FCPyoaA2cIiPo0-l4aiA?via=ubuntu.com&via=matrix.org&via=matrix.debian.social