e2e(kafka): the suite leaves about 40 GiB of broker PVCs behind in tenant-test #4616

The kafka e2e suite leaves its broker PVCs behind in tenant-test, about 40 GiB per run, and later suites in the same sandbox pay for it.

Both node pools set deleteClaim: false (packages/apps/kafka/templates/migration-hook.yaml), which is intended: the README says to delete the volumes by hand after removing the app. hack/e2e-chainsaw/kafka/chainsaw-test.yaml deletes the app but never the volumes. In nightly run 36659663201 the PV snapshot taken after the kubernetes suites still shows them Bound: data-0-kafka-test-b-*-0/1 at 10Gi each and data-0-kafka-test-c-*-2/3/4 at 5Gi each, created at 03:03. 20 GiB of that sits on srv2, which is what kept srv2 below the replicated-lane pool floor and failed both kubernetes suites in that run (#4617).

Fix shape: the suite deletes the PVCs in its own cleanup, e.g. by the strimzi.io/cluster label for each test cluster, and waits for them to go.