nodeagent DaemonSet delete missing errors.IsNotFound check, causes DeleteDaemonSetFailed / test flakiness

Bug

The node-agent DaemonSet deletion path doesn't check errors.IsNotFound(err) before treating a delete failure as a real error — unlike the adjacent ConfigMap deletion path in the same reconciler, which does handle this correctly.

// DaemonSet path (missing IsNotFound check):
if err := r.Delete(deleteContext, ds, &client.DeleteOptions{...}); err != nil {
    r.EventRecorder.Event(...)
    return false, err  // should treat IsNotFound as success (already gone)
}

Recommended fix: add errors.IsNotFound(err) handling after the r.Delete() call — when the delete fails with NotFound, treat it as success (the DaemonSet is already gone), matching the ConfigMap path's existing behavior.

Affected versions (confirmed present in all)

How this was found

Surfaced by this repo's own automated e2e log-analysis tooling on ci/prow/4.23-e2e-test-aws for PR #2206 (oadp-1.6, unrelated change — veleroPredicate/annotation-change reconciliation): the AfterEach cleanup of "Configuration testing for DPA Custom Resource" (tests/e2e/dpa_deployment_suite_test.go) hit a DeleteDaemonSetFailed event while the velero pod was stuck PodInitializing, failing the test. The analysis explicitly concluded: "Likely Cause: Real bug in the OADP operator's DaemonSet reconciliation logic. Not a flake, not environmental." None of the known-flake patterns in tests/e2e/lib/flakes.go matched.

Log: https://prow.ci.openshift.org/view/gs/test-platform-results/pr-logs/pull/openshift_oadp-operator/2206/pull-ci-openshift-oadp-operator-oadp-1.6-4.23-e2e-test-aws/2087353890981810176

This appears to be a pre-existing, long-standing bug rather than something introduced by #2206 — it just happened to get exercised by that PR's e2e run.

[!Note]
Responses generated with Claude

Start with the DaemonSet deletion path in internal/controller/nodeagent.go, or controllers/nodeagent.go for the oadp-1.4 branch, and compare it with the adjacent ConfigMap deletion path. Review the cleanup scenario in tests/e2e/dpa_deployment_suite_test.go and the related CI log. Done means NotFound deletion is treated as success without a DeleteDaemonSetFailed event or reconciliation failure.