Can't delete namespaces from test environment

I'd like to use namespaces to isolate my tests from one another. For example, I want to create a new namespace with a random name in my `BeforeEach` and delete it in `AfterEach` so that individual tests don't have to worry about cleaning up after themselves.

However, I've observed that namespace deletion doesn't work when using `envtest`. When I delete a namespace, the deletion timestamp on resources within that namespace remain unset, and the namespace stays in the `Terminating` phase seemingly forever. The latter is true even if the namespace is empty (e.g. I delete it immediately after creating it).

Is this behavior expected? Is whatever mechanism that normally executes namespace deletion missing from `envtest`?

No file or test is named. Start by reproducing namespace creation and deletion in envtest, then inspect resource deletion timestamps and the namespace phase; done should establish whether this behavior is expected and, if not, verify that deletion completes.

Written by the indexing model from the issue text.