Namespace deletion in testing is not working as intended.

[kannon92]

Generally Kubebuilder does not support deletion of namespaces. https://book.kubebuilder.io/reference/envtest.html#namespace-usage-limitation

kubernetes-sigs/controller-runtime#880

Due to this, I think we should update our tests to delete a namespace. I ran into some oddness with #101.

My proposal would be to remove the cleanup of namespaces and make sure the objects that get created are removed correctly.

[kannon92]

/assign

[ahg-g]

yeah, because the gc that deletes the objects is not started as part of the integration tests;

what we did with kueue was to manually delete the objects; we can do the same here: https://github.com/kubernetes-sigs/kueue/blob/main/test/util/util.go#L79