Dask operator runs in dask-system namespace

[daachi]

Dask operator is currently installed in the radps-hub namespace whereas it should be moved to the cluster level.

Acceptance Criteria:

• kubectl get pods -n dask-system shows the operator running
• kubectl get pods -n radps-hub shows no dask-operator pod
• A test DaskCluster resource created in radps-hub is reconciled correctly by the operator
• Documentation is validated by the science team