ci: use kube-apiserver v1.25.16 for k8s 1.25 CI

[jmdeal]

Fixes #803

Description
This PR downloads kube-apiserver v1.25.16 for use with envtest when running CI jobs for k8s 1.25.

How was this change tested?
Running GitHub actions after opening the PR.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[k8s-ci-robot]

@jmdeal: 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-karpenter-test-1-29	6b2ee0f	link	false	/test pull-karpenter-test-1-29
pull-karpenter-test-1-26	6b2ee0f	link	false	/test pull-karpenter-test-1-26
pull-karpenter-test-1-28	6b2ee0f	link	false	/test pull-karpenter-test-1-28
pull-karpenter-test-1-27	6b2ee0f	link	false	/test pull-karpenter-test-1-27

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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[jonathan-innis]

LGTM 🚀 Thanks so much! Awesome work here!

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jmdeal, jonathan-innis

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[jonathan-innis]

/lgtm