Containers remain running after exiting

In particular, this means it's impossible to remove a toolbox-created container without first stopping/killing it with `podman`:

```
~/toolbox  ./toolbox create -c test
Created container: test
Enter with: toolbox enter --container test
~/toolbox  ./toolbox enter -c test
🔹[exalm@toolbox toolbox]$ logout
~/toolbox  ./toolbox rm test
toolbox: failed to remove container test
~/toolbox  podman ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
1a08f09ea797 localhost/fedora-toolbox-exalm:30 sleep +Inf 16 seconds ago Up 10 seconds ago test
~/toolbox  podman stop test
1a08f09ea79710801859bea8dc6a5a85d2031ce1a73dd7d284c3e1fa51a67be0
~/toolbox  ./toolbox rm test
~/toolbox 
```