Check for sufficient available free IP space before marking a subnet as useable

[cbajumpaa]

Include suggested changes from PR #1233

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[k8s-ci-robot]

Hi @cbajumpaa. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: cbajumpaa
To complete the pull request process, please assign bigkraig
You can assign the PR to them by writing /assign @bigkraig in a comment when ready.

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[M00nF1sh]

/lgtm
/ok-to-test

[M00nF1sh]

/check-cla

[k8s-ci-robot]

@cbajumpaa: The following test failed, say /retest to rerun all failed tests:

Test name	Commit	Details	Rerun command
pull-aws-alb-ingress-controller-lint	d74ddba	link	/test pull-aws-alb-ingress-controller-lint

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository. I understand the commands that are listed here.