Hardcoded namespace in spire charts

**Describe the bug**

In `spire-bundle-cfg.yaml`, this:

```yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: spire-bundle
namespace: spire
```

Should probably be this:

```yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: spire-bundle
namespace: {{ .Release.Namespace }}
```

Otherwise, this will happen when you try to install to a different namespace:

```
time="2023-06-07T20:06:58Z" level=error msg="Server crashed" error="one or more notifiers returned an error: rpc error: code = Internal desc = notifier(k8sbundle): unable to update: unable to get list: configmaps \"spire-bundle\" is forbidden: User \"system:serviceaccount:spire2:spire-server\" cannot get resource \"configmaps\" in API group \"\" in the namespace \"spire\""
```

Open spire-bundle-cfg.yaml and inspect how the ConfigMap namespace is rendered by the chart. Install the chart into a namespace other than spire, then verify that the rendered ConfigMap and SPIRE server access use the installation namespace without the reported permission error.

Written by the indexing model from the issue text.