deployment: default temporal namespace

When deploying orcha with temporal, a namespace is not created automatically. We could consider creating the default namespace when deploying, although the current solution might be sufficient. Currently, when installing the helm chart (and not when upgrading), we need to create the namespace by:

```bash
$ oc exec -it services/temporal-admintools /bin/bash
bash-5.0#
```

And using the [temporal CLI](https://docs.temporal.io/cli) to create the namespace `default`:
```bash
temporal operator namespace create -n default
```