add default proxy-body-size in controlplane ingress

This for example is added to the CAS 

```
 nginx.ingress.kubernetes.io/proxy-body-size: "100m"
```

in the controlplane you might get 

- [ ] ```

chainloop att push i got
ERR pushing to control plane: storing attestation: rpc error: code = Unknown desc = unexpected HTTP status code received from server: 413 (Request Entity Too Large); transport: received unexpected content-type "text
```