fix e2e-tests

[cpanato]

What type of PR is this?

/kind bug

What this PR does / why we need it:

• fix e2e-tests
  e2e postsubmit tests were failing for a long time, this PR fix the tests

green run: https://github.com/kubernetes-sigs/release-sdk/actions/runs/8508551487/job/23302306978

/assign @saschagrunert @puerco @xmudrii
cc @kubernetes-sigs/release-engineering

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

Does this PR introduce a user-facing change?

fix e2e tests for image signing 

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cpanato

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [cpanato]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[cpanato]

/hold

[saschagrunert]

The appending of unknownRefsTemp to unknownRefs changes the initial logic in line 363. This will also make the test fail:

release-sdk/sign/sign_test.go

Lines 338 to 352 in c76d421

	{ // Skip on no signatures listed
	fakeReference: &FakeReferenceStub{
	image: "gcr.io/fake/honk:99.99.99",
	registry: "gcr.io",
	repository: "fake/honk",
	},
	prepare: func(mock *signfakes.FakeImpl) {
	m := &sync.Map{}
	m.Store("gcr.io/fake/honk:99.99.99", false)
	mock.ImagesSignedReturns(m, nil)
	},
	assert: func(obj *sign.SignedObject, err error) {
	require.Nil(t, err)
	require.Nil(t, obj)
	},

[cpanato]

/test pull-release-sdk-integration-test
/test pull-release-sdk-test

[saschagrunert]

I hope we don't regress anything with that. Let's add a release note mentioning the behavioral change.

[cpanato]

latest e2e run: https://github.com/kubernetes-sigs/release-sdk/actions/runs/8519998461/job/23335219938

[k8s-ci-robot]

@cpanato: 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-release-sdk-verify	9ceba1b	link	true	/test pull-release-sdk-verify
pull-release-sdk-integration-test	835317f	link	true	/test pull-release-sdk-integration-test

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.

[cpanato]

closing this in favor of another branch with the correct fix