Remove external-attacher from the repo.

# Describe the bug #

The presence of external-attacher adds on overhead and issues wrt attachment in various scenarios. One of them would be the lack of performance on syncing volumeattachment from api server..etc. More or less we don't have controller publish and unpublish capabilities , so we should not make use of this sidecar and cause unnecessary addon here thus other issues.

The solution:

Make use of `skip attach` field in CSI Driver object.

```
apiVersion: storage.k8s.io/v1
kind: CSIDriver
metadata:
name: mycsidriver.example.com
spec:
attachRequired: false
```