Bug: delete Dataset and containing namespace in quick succession can result in finalizer hang

[starpit]

the dataset-operator logs show lots of this:

1.7105266916204755e+09 ERROR controller.dataset Reconciler error {"reconciler group": "com.ie.ibm.hpsys", "reconciler kind": "Dataset", "name": "xxxx", "namespace": "yyyy", "error": "datasetsinternal.com.ie.ibm.hpsys "xxxx" is forbidden: unable to create new content in namespace yyyy because it is being terminated"}
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem
/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.11.0/pkg/internal/controller/controller.go:266
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2
/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.11.0/pkg/internal/controller/controller.go:227