aws: Update VPC CNI to v1.18.4

[hakman]

/cc @rifelpet @justinsb

[k8s-ci-robot]

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[hakman]

/test pull-kops-e2e-cni-amazonvpc

[hakman]

/test pull-kops-e2e-aws-upgrade-k127-ko127-to-klatest-kolatest-many-addons
/test pull-kops-e2e-cni-amazonvpc

[hakman]

/test pull-kops-e2e-aws-upgrade-k129-ko129-to-klatest-kolatest-many-addons

[k8s-ci-robot]

@hakman: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-kops-e2e-aws-upgrade-k127-ko127-to-klatest-kolatest-many-addons	a5fdc9a	link	false	/test pull-kops-e2e-aws-upgrade-k127-ko127-to-klatest-kolatest-many-addons
pull-kops-e2e-cni-amazonvpc	a5fdc9a	link	true	/test pull-kops-e2e-cni-amazonvpc

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.

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