Investigate need for k8s prestart-pull-pause-ctr

[stmcginnis]

Description:

We currently have a drop-in for the pause container. @bcressey raised the question about it here: #3046 (comment)

https://github.com/bottlerocket-os/bottlerocket/blob/develop/packages/kubernetes-1.22/prestart-pull-pause-ctr.conf

We should add comments explaining why it is needed, or determine if there is anything to be done to drop it.

Possibly related, all current k8s variants no longer need dockershim.sock once 1.22 is dropped, but this file refers to it. If it's the just for this, we should see if it can be dropped.

[stmcginnis]

I was able to track down when and why this was introduced: #382

Updating PR to implement image fetch from ECR before kubelet starts so containerd is able to start pause containers without needing to auth to ECR (which it cannot do),

Tried removing the pull from a build. Deploying the node failed to join the cluster. Got log messages indicating the original reason for adding this still appears to be true.

Jun 27 13:03:54 ip-192-168-32-115.us-east-2.compute.internal kubelet[1168]: E0627 13:03:54.982296    1168 pod_workers.go:965] "Error syncing pod, skipping" err="failed to \"CreatePodSandbox\" for \"aws-node-7kprb_kube-system(66688bb4-0a4c-42db-9286-d79d2acb027d)\" with CreatePodSandboxError: \"Failed to create sandbox for pod \\\"aws-node-7kprb_kube-system(66688bb4-0a4c-42db-9286-d79d2acb027d)\\\": rpc error: code = Unknown desc = failed to get sandbox image \\\"602401143452.dkr.ecr.us-east-2.amazonaws.com/eks/pause:3.1-eksbuild.1\\\": failed to pull image \\\"602401143452.dkr.ecr.us-east-2.amazonaws.com/eks/pause:3.1-eksbuild.1\\\": failed to pull and unpack image \\\"602401143452.dkr.ecr.us-east-2.amazonaws.com/eks/pause:3.1-eksbuild.1\\\": failed to resolve reference \\\"602401143452.dkr.ecr.us-east-2.amazonaws.com/eks/pause:3.1-eksbuild.1\\\": pulling from host 602401143452.dkr.ecr.us-east-2.amazonaws.com failed with status code [manifests 3.1-eksbuild.1]: 401 Unauthorized\"" pod="kube-system/aws-node-7kprb" podUID=66688bb4-0a4c-42db-9286-d79d2acb027d