[Flaky Test] pull-gardener-e2e-kind-ipv6 is flaky

[ialidzhikov]

How to categorize this issue?

/area testing
/kind flake

Which test(s)/suite(s) are flaking:

• Shoot Tests Create Shoot, Rotate Credentials and Delete Shoot Shoot with workers with workers rollout, in-place update strategy [It] Wait for Shoot to be reconciled [Shoot, default, credentials-rotation, basic, with-workers-rollout, in-place]

CI link:

• https://prow.gardener.cloud/view/gs/gardener-prow/pr-logs/pull/gardener_gardener/11840/pull-gardener-e2e-kind-ipv6/1919710993244491776
• https://prow.gardener.cloud/view/gs/gardener-prow/pr-logs/pull/gardener_gardener/11840/pull-gardener-e2e-kind-ipv6/1919662288369881088
• https://prow.gardener.cloud/view/gs/gardener-prow/pr-logs/pull/gardener_gardener/12018/pull-gardener-e2e-kind-ipv6/1919803370655191040
• https://prow.gardener.cloud/view/gs/gardener-prow/pr-logs/pull/gardener_gardener/12018/pull-gardener-e2e-kind-ipv6/1920033546995503104

Other failures:

• https://prow.gardener.cloud/view/gs/gardener-prow/pr-logs/pull/gardener_gardener/11840/pull-gardener-e2e-kind-ipv6/1919763964196032512

Reason for failure:

• [TIMEDOUT] [1800.002 seconds]
Shoot Tests Create Shoot, Rotate Credentials and Delete Shoot Shoot with workers with workers rollout, in-place update strategy [It] Wait for Shoot to be reconciled [Shoot, default, credentials-rotation, basic, with-workers-rollout, in-place]
/home/prow/go/src/github.com/gardener/gardener/test/e2e/gardener/shoot/create_rotate_delete.go:103
  Timeline >>
  > Enter [BeforeEach] TOP-LEVEL @ 05/06/25 18:19:25.771
  < Exit [BeforeEach] TOP-LEVEL @ 05/06/25 18:19:25.771 (0s)
  > Enter [It] Wait for Shoot to be reconciled @ 05/06/25 18:19:25.771
...
  2025-05-06T18:47:56.127Z	INFO	Waiting for reconciliation and healthiness	{"shoot": {"name":"e2e-rot-ip","namespace":"garden-local"}, "lastOperation": "&LastOperation{Description:Removing label from resources after modification of encryption config or rotation of ETCD encryption key,LastUpdateTime:2025-05-06 18:42:22 +0000 UTC,Progress:98,State:Processing,Type:Reconcile,}", "reason": "last operation type was create, reconcile or restore but state was not succeeded"}
  2025-05-06T18:48:26.133Z	INFO	Waiting for reconciliation and healthiness	{"shoot": {"name":"e2e-rot-ip","namespace":"garden-local"}, "lastOperation": "&LastOperation{Description:Removing label from resources after modification of encryption config or rotation of ETCD encryption key,LastUpdateTime:2025-05-06 18:42:22 +0000 UTC,Progress:98,State:Processing,Type:Reconcile,}", "reason": "last operation type was create, reconcile or restore but state was not succeeded"}
  2025-05-06T18:48:56.139Z	INFO	Waiting for reconciliation and healthiness	{"shoot": {"name":"e2e-rot-ip","namespace":"garden-local"}, "lastOperation": "&LastOperation{Description:Removing label from resources after modification of encryption config or rotation of ETCD encryption key,LastUpdateTime:2025-05-06 18:42:22 +0000 UTC,Progress:98,State:Processing,Type:Reconcile,}", "reason": "last operation type was create, reconcile or restore but state was not succeeded"}
  [TIMEDOUT] in [It] - /home/prow/go/src/github.com/gardener/gardener/test/e2e/gardener/shoot/create_rotate_delete.go:103 @ 05/06/25 18:49:25.771
  [FAILED] in [It] - /home/prow/go/src/github.com/gardener/gardener/test/e2e/gardener/shoot/shoot.go:165 @ 05/06/25 18:49:25.772
  < Exit [It] Wait for Shoot to be reconciled @ 05/06/25 18:49:25.773 (30m0.001s)```

**Anything else we need to know**:
![Image](https://github.com/user-attachments/assets/f41ba4db-551e-4386-bc29-c924c29edfd5)

[ialidzhikov]

From IPv6 docs:

Developing or testing IPv6-related features requires a Linux machine (docker only supports IPv6 on Linux) and native IPv6 connectivity to the internet.

I don't have such a Linux machine under hand to be able to proceed with the investigation.

/unassign

[ialidzhikov]

The corresponding test is skipped now for ipv6 with #12020.

I will keep the issue open so that we don't forget to debug and eventually fix the skipped test for ipv6.

cc @shafeeqes @acumino @ary1992