Validate cluster after updating bastions

[johngmyers]

/kind bug

The fix #7872 exposed an issue where rolling update starts updating the first master before the terminated bastion is replaced by the ASG. Before that fix, kops was relying on the fact that the resulting validation failure was ignored.

This fixes the issue by waiting for validation to succeed after terminating a bastion. It does not change the behavior of updating the first bastion without validating the cluster.

The other possible fix would be to make validation ignore any shortfall in members of bastion instance groups.

Fixes #8070

[k8s-ci-robot]

Hi @johngmyers. Thanks for your PR.

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[rifelpet]

/ok-to-test

[johngmyers]

/test pull-kops-e2e-kubernetes-aws

[zetaab]

thanks @johngmyers for fixing this!

/approve
/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: johngmyers, zetaab

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[zetaab]

@johngmyers could you please cherry-pick this to release-1.17 as it is "broken" there

[johngmyers]

Is there a procedure for cherry picking other than just raising a PR?

[zetaab]

at least i am not aware of any other

[rifelpet]

Theres a convenient script for cherry picking that is documented here