exit 0 after checking addon configmap existences

[pacoxu]

Fixes https://testgrid.k8s.io/sig-cluster-lifecycle-kubeadm#kubeadm-kinder-no-addons-latest
Fixes #3144

# task-08-check-addons-after-upgrade
/bin/sh -c docker exec kinder-upgrade-control-plane-1 kubectl get cm kube-proxy -n kube-system --kubeconfig /etc/kubernetes/admin.conf && exit 1
docker exec kinder-upgrade-control-plane-1 kubectl get cm coredns -n kube-system --kubeconfig /etc/kubernetes/admin.conf && exit 1
Error from server (NotFound): configmaps "kube-proxy" not found
Error from server (NotFound): configmaps "coredns" not found
 exit status 1

/cc @neolit123

[pacoxu]

The failure is introduced by https://github.com/kubernetes/kubeadm/pull/3138/files#diff-c2d18f5e6eb678a16f280f2655d28a1682795ca8f19a900eae6b08a67f523043R107-R116 yesterday.

[neolit123]

i still don't exactly understand why this is needed, but we do have it in other places. so LGTM.

thanks
/lgtm

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[neolit123]

i still don't exactly understand why this is needed, but we do have it in other places. so LGTM.

thanks /lgtm

i guess it just takes the exit status of the last failed command.