Fix delete wait helpers to poll requested objects

[immanuwell]

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Please add a summary of your change

Fixes three delete-wait helpers that deleted the requested object, then polled the namespace name instead of the object name. Tiny cleanup footgun, but it can make E2E cleanup lie or wait on the wrong thing when ns != name.

Does your change fix a particular issue?

No related issue found.

Repro:

• change the helper poll calls back from name to ns
• run go test ./test/util/k8s -run 'TestWaitFor.*DeletePolls' -count=1
• tests fail with expected get action for "test-service", got "test-ns" and same deal for Secret/ConfigMap

Checked:

• go test ./test/util/k8s ./test/util/velero -count=1

Please indicate you've done the following:

• Accepted the DCO. Commits without the DCO will delay acceptance.
• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main (not needed; no docs behavior changed).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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