The :latest tag caused E2E flakiness when a newer Headlamp image was
pulled on some cluster nodes (IfNotPresent policy) but not others.
Concurrent E2E runs on main saw different image versions, and the newest
:latest (sha256:89c6c65) failed to pass the readiness probe within 120s.
Pin to v0.40.1 — the same version running in production (kube-system) —
so all nodes use the same cached digest and CI is deterministic. Update
this pin when Headlamp is upgraded in production.
Co-Authored-By: Paperclip <noreply@paperclip.ing>