`btrbk clean` commands are not runnable for ssh:// targets

I get asked to `delete stray subvolumes`:

```
Checking for missing backups of subvolume "/media/ssd/btrbk/home-var" in "nas[5090]:/btrbk/svelte/home-var/"
WARNING: Target subvolume "nas[5090]:/btrbk/svelte/home-var/home-var.20250314T1600" exists, but is not a receive target of "/media/ssd/btrbk/home-var/home-var.202
50314T1600"
WARNING: Please delete stray subvolumes: "btrbk clean nas[5090]:/btrbk/svelte/home-var"
WARNING: Skipping backup of: /media/ssd/btrbk/home-var/home-var.20250314T1600
```

```
% btrbk clean nas[5090]:/btrbk/svelte/home-var
zsh: no matches found: nas[5090]:/btrbk/svelte/home-var
```

Ok, adding quotes (shell-quote is a perl module I think?) would be nice, but I can do that:
```
% sudo btrbk clean 'nas[5090]:/btrbk/svelte/home-var' --lockfile /tmp/nas
ERROR: Filter argument "nas[5090]:/btrbk/svelte/home-var" does not match any volume, subvolume, target or group declaration
```

The command that should be output is:
```
sudo btrbk clean 'ssh://nas:5090/btrbk/svelte/home-var
```