OCPBUGS-67322: Fix CVE-2025-66564 by updating build tooling

[aman4433]

This PR fixes CVE-2025-66564 by updating build-time tooling under hack/tools,
including upgrading cosign to v2, which removes the vulnerable
timestamp-authority v1 dependency.

[openshift-ci-robot]

@aman4433: This pull request references Jira Issue OCPBUGS-67322, which is invalid:

• release note text must be set and not match the template OR release note type must be set to "Release Note Not Required". For more information you can reference the OpenShift Bug Process.
• expected dependent Jira Issue OCPBUGS-67324 to be in one of the following states: VERIFIED, RELEASE PENDING, CLOSED (ERRATA), CLOSED (CURRENT RELEASE), CLOSED (DONE), CLOSED (DONE-ERRATA), but it is New instead

Comment /jira refresh to re-evaluate validity if changes to the Jira bug are made, or edit the title of this pull request to link to a different bug.

The bug has been updated to refer to the pull request using the external bug tracker.

Details

In response to this:

This PR fixes GHSA-4qg8-fj49-pxjh by updating build-time tooling under hack/tools,
including upgrading cosign to v2, which removes the vulnerable
timestamp-authority v1 dependency.

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[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[openshift-ci]

@aman4433: 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
ci/prow/unit	5bb0d2f	link	true	/test unit
ci/prow/generate	5bb0d2f	link	true	/test generate

Full PR test history. Your PR dashboard.

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