Removing a Cloud from juju generates an error message, but also removes it

[Jonatas Baldin]

Removing a local Cloud from client and controller removes it, but also outputs an error message. As a user, I expect it to work successfully or fail gracefully not an in between state.

"microk8s" cloud is there:
```
$ juju list-clouds
Only clouds with registered credentials are shown.
There are more clouds, use --all to see them.

Clouds available on the controller:
Cloud Regions Default Type
my-k8s 0 k8s

Clouds available on the client:
Cloud Regions Default Type Credentials Source Description
localhost 1 localhost lxd 0 built-in LXD Container Hypervisor
microk8s 1 localhost k8s 0 local A Kubernetes Cluster
minikube 0 k8s 0 local A Kubernetes Cluster
my-k8s 0 k8s 1 local A Kubernetes Cluster
mycluster 1 localhost k8s 0 local A Kubernetes Cluster
```

Removing it:
```
$ juju remove-cloud microk8s
This operation can be applied to both a copy on this client and to the one on a controller.
Do you want to remove cloud microk8s from:
    1. client only (--client)
    2. controller "my-k8s" only (--controller my-k8s)
    3. both (--client --controller my-k8s)
Enter your choice, or type Q|q to quit: 3
Removed details of cloud "microk8s" from the client
ERROR cloud "microk8s" not found
```

Outputs a successful message AND an error:
```
$ juju list-clouds
Only clouds with registered credentials are shown.
There are more clouds, use --all to see them.

Clouds available on the controller:
Cloud Regions Default Type
my-k8s 0 k8s

Clouds available on the client:
Cloud Regions Default Type Credentials Source Description
localhost 1 localhost lxd 0 built-in LXD Container Hypervisor
my-k8s 0 k8s 1 local A Kubernetes Cluster
mycluster 1 localhost k8s 0 local A Kubernetes Cluster
```

Output status is also an error:
```
$ echo $?
1
```

[Achilleas Anagnostopoulos (achilleasa)]

PR https://github.com/juju/juju/pull/12684 contains a fix for 2.9