Get rid of exclude directive for v0.27.1 of k8s.io/api, k8s.io/client-go and clean up workarounds

[programmer04]

Is there an existing issue for this?

• I have searched the existing issues

Problem Statement

Due to problems with upstream dependency sigs.k8s.io/controller-runtime

• ✨ upgrade to k8s 0.27.1 kubernetes-sigs/controller-runtime#2189
• Bump to k8s.io/ v0.27.2 kubernetes-sigs/controller-runtime#2297 -> 🌱 Re-enable tests for v0.27.2 kubernetes-sigs/controller-runtime#2333

we have to wait for release of v0.15.0 to be able to get rid exclude directive for v0.27.1 of k8s.io/api, k8s.io/client-go and update them. During development a workaround was required to finish #3916. This issue is supposed to track work to do to have everything by the book.

Proposed Solution

• Wait for https://sigs.k8s.io/controller-runtime v0.15.0

• Upgrade it and get rid of

  kubernetes-ingress-controller/go.mod

  Lines 8 to 13 in ef5a0e3

  	exclude (
  	// NOTE: excluded until https://github.com/kubernetes-sigs/controller-runtime/pull/2189
  	// gets resolved
  	k8s.io/api v0.27.1
  	k8s.io/client-go v0.27.1
  	)

• Clean up workaround introduced by chore(tests): workaround to not rely on helpers from KTF #3980 - ensure that github.com/kong/kubernetes-testing-framework is upgraded to a version that contains PR feat(k8s): Switch from CoreV1 Endpoints to DiscoveryV1 EndpointSlice kubernetes-testing-framework#643

Additional information

No response

Acceptance Criteria

• directive exclude for v0.27.1 of k8s.io/api, k8s.io/client-go is removed
• Helpers introduced in chore(tests): workaround to not rely on helpers from KTF #3980 are removed (go back to importing them from KTF)