Remove SeparateTaintEvictionController feature gate

[wasylkowski-a]

What type of PR is this?

/kind cleanup
/sig scheduling

What this PR does / why we need it:

Removes the SeparateTaintEvictionController feature gate from Kubernetes. The feature gate graduated to GA in v1.34 and has completed the required 3-release version emulation deprecation window.

This PR:

• Removes SeparateTaintEvictionController feature gate from pkg/features/kube_features.go.
• Removes required feature gate check on newTaintEvictionControllerDescriptor in cmd/kube-controller-manager/app/core.go.
• Removes legacy embedded taint manager in NodeLifecycleController (pkg/controller/nodelifecycle/node_lifecycle_controller.go).
• Updates unit tests in cmd/kube-controller-manager/app/controllermanager_test.go to test standalone taint eviction controller directly without feature gating.
• Cleans up integration tests in test/integration/node/lifecycle_test.go.
• Updates compatibility lifecycle reference documentation (versioned_feature_list.yaml and feature_list.md).

Which issue(s) this PR fixes:

KEP: kubernetes/enhancements#3902

Special notes for your reviewer:

AI was used in preparing and verifying this change. The author carefully reviewed the code before submitting the PR.

Does this PR introduce a user-facing change?

action required: Removed the `SeparateTaintEvictionController` feature gate from `kube-controller-manager` as the separate taint eviction controller is now permanently enabled.

[kubernetes-prow]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: wasylkowski-a
Once this PR has been reviewed and has the lgtm label, please assign deads2k, sergeykanzhelev for approval. For more information see the Code Review Process.

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Details

Needs approval from an approver in each of these files:

• cmd/kube-controller-manager/OWNERS
• pkg/controller/nodelifecycle/OWNERS
• pkg/features/OWNERS
• test/compatibility_lifecycle/reference/OWNERS
• test/integration/node/OWNERS

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[kubernetes-prow]

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[kubernetes-prow]

Hi @wasylkowski-a. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work.

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Details

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[wasylkowski-a]

/assign @jdzikowski

[jdzikowski]

/ok-to-test

[wasylkowski-a]

Fixed formatting.

[jdzikowski]

/lgtm

[kubernetes-prow]

LGTM label has been added.

Details

Git tree hash: 93477601d433e69b8cfec409582135c394feaf04

[pacoxu]

action required: Removed the SeparateTaintEvictionController feature gate from kube-controller-manager as the separate taint eviction controller is now permanently enabled.

The wording “the separate taint eviction controller is now permanently enabled” may be misleading. The standalone implementation is now permanent, but the controller itself can still be disabled using --controllers=-taint-eviction-controller.

A suggested release note is like below.

action required: Removed the `SeparateTaintEvictionController` feature gate from `kube-controller-manager`. Remove this gate from existing `--feature-gates` configuration before upgrading. Taint-based eviction is now permanently implemented by the standalone taint eviction controller, which can still be disabled using `--controllers=-taint-eviction-controller`.

Also, please follow up in the kubernetes/website repository’s dev-1.38 branch to mark this feature gate as removed and update any current references accordingly. Documentation for --controllers=-taint-eviction-controller should remain, as that option is still supported.

/cc @yuanchen8911 @atosatto
feature owners

[pacoxu]

/lgtm

[kubernetes-prow]

LGTM label has been added.

Details

Git tree hash: c1303c3d11f83001f43f55e95bd1ed0f86b96329