KEP-5067: correct details about mirror pod implementation

[natasha41575]

• One-line PR description:
  Correcting the details about how generation / observedGeneration are handled for mirror pods. Based on discussion in the kep and implementation prs we aren't doing anything special, so generation and observedGeneration on a mirror pod will always be 1.

• Discussion comments:

  • KEP 5067: Pod Generation KEP creation #5068 (comment)
  • start setting pod metadata.generation kubernetes#130181 (comment)
  • [FG:PodObservedGenerationTracking] Kubelet sets pod status.observedGeneration when updating the pod status kubernetes#130352 (comment)

• Issue link: Pod Generation #5067

/sig node
/assign @mrunalp

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: natasha41575
Once this PR has been reviewed and has the lgtm label, please assign dchen1107 for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• keps/sig-node/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[natasha41575]

/assign @tallclair

(not urgent)