operator: hostNetwork Deployments can hit a brief zero-available window on rollout

[plombardi89]

The hostNetwork unbounded-net-controller and metalman Deployments use RollingUpdate with maxSurge: 0 because the old and new pods would otherwise bind the same host ports. As a result the old pod terminates before the new one starts, so a broken new image causes a brief window where AvailableReplicas == 0.

Follow-up / operational hardening:

• Roll back on failed rollout.
• Alert on AvailableReplicas == 0 for these Deployments.
• Consider rollout guardrails (e.g. readiness gating, progressDeadlineSeconds tuning) to bound the window.

Context: split out of the umbrella unbounded-system integration PR #388.