users module does not allow ssh_import_id and ssh_authorized_keys at the same time

This bug was originally filed in Launchpad as [LP: #1997588](https://bugs.launchpad.net/cloud-init/+bug/1997588)

Launchpad details

affected_projects = []

assignee = None

assignee_name = None

date_closed = None

date_created = 2022-11-23T18:01:01.031774+00:00

date_fix_committed = None

date_fix_released = None

id = 1997588

importance = medium

is_complete = False

lp_url = https://bugs.launchpad.net/cloud-init/+bug/1997588

milestone = None

owner = nrobinaubertin

owner_name = Niels Robin-Aubertin

private = False

status = triaged

submitter = nrobinaubertin

submitter_name = Niels Robin-Aubertin

tags = []

duplicates = []

_Launchpad user **Niels Robin-Aubertin(nrobinaubertin)** wrote on 2022-11-23T18:01:01.031774+00:00_

I'm on ubuntu 22.04, using multipass 1.10.1 with a cloud-init file to instanciate a simple server:

```yaml
users:
- name: ubuntu
ssh_authorized_keys:
- ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIOkF+W1ETkZQr5PWhcugCVh3aSyNDFTYQRRblh7prGXN
ssh_import_id:
- lp:nrobinaubertin
```

I launch the instance with:
```shell
multipass launch -n simple_instance -d 10G -m 1G -c 1 --cloud-init cloud-init.yaml 22.04
```

And I check the authkeys file with:
```shell
multipass exec simple_instance -- cat /home/ubuntu/.ssh/authorized_keys
```

The key from `ssh_authorized_keys` is there but not the one from `ssh_import_id`.
From the documentation website and the examples given [here](https://cloudinit.readthedocs.io/en/latest/topics/examples.html) I would expect both keys to be present.