[Sri Harsha (SriHarsha001)]

What this PR does / why we need it:

• Set clusterDNS in the kubelet config file when config-file mode is enabled.
• Use --cluster-dns only in CLI mode, avoiding KUBELET_FLAGS differences between ANC and NBC.
• Add regression coverage for the affected LocalDNS scenarios.

Which issue(s) this PR fixes:

Fixes #

[github-actions]

Windows Unit Test Results

  3 files   18 suites   1m 10s ⏱️
563 tests 563 ✅ 0 💤 0 ❌
585 runs  585 ✅ 0 💤 0 ❌

Results for commit ee9af9c.

[github-actions]

Package	Line Rate	Health
test	0%	❌
windows	27%	❌
staging_cse_windows Package 1	65%	➖
debug	0%	❌
provisioningscripts	2%	❌
parts_windows Package 1	73%	➖
Summary	38% (1652 / 6834)	❌

[github-actions]

Package	Line Rate	Health
shellspec spec	28%	❌
Summary	28% (4556 / 15971)	❌

[github-actions]

Package	Line Rate	Health
github.com/Azure/agentbaker/aks-node-controller	72%	➖
github.com/Azure/agentbaker/aks-node-controller/common	100%	✔
github.com/Azure/agentbaker/aks-node-controller/helpers	68%	➖
github.com/Azure/agentbaker/aks-node-controller/parser	88%	✔
github.com/Azure/agentbaker/aks-node-controller/pkg/gpu	100%	✔
github.com/Azure/agentbaker/aks-node-controller/pkg/nodeconfigutils	89%	✔
github.com/Azure/agentbaker/aks-node-controller/utils	0%	❌
github.com/Azure/agentbaker/apiserver	24%	❌
github.com/Azure/agentbaker/cmd	0%	❌
github.com/Azure/agentbaker/cmd/starter	0%	❌
github.com/Azure/agentbaker/fuzz/api	0%	❌
github.com/Azure/agentbaker/hotfix/render-nodecustomdata	0%	❌
github.com/Azure/agentbaker/pkg/agent	78%	➖
github.com/Azure/agentbaker/pkg/agent/datamodel	77%	➖
github.com/Azure/agentbaker/pkg/agent/toggles	0%	❌
github.com/Azure/agentbaker/pkg/vhdbuilder/datamodel	87%	✔
Summary	74% (5838 / 7824)	➖

[Copilot]

🟢 Approval recommended

The narrow E2E changes match the existing conversion contract, with no blocking defects identified; tests were not executed.

No open issues 🎉

What changed in this PR

This PR aligns LocalDNS E2E kubelet settings with the selected configuration mode, preserving parity between CSE and aks-node-controller provisioning.

Changes:

• Set ClusterDns when kubelet config files are enabled; otherwise set --cluster-dns.
• Add a regression test verifying that LocalDNS mutators preserve config-file settings without reintroducing the flag.

File	Description
e2e/​scenario/​scenario_localdns_hosts.go	Selects the appropriate DNS setting for hosts-plugin scenarios.
e2e/​scenario/​scenario_localdns_fallback.go	Applies the same configuration-mode handling to fallback scenarios.
e2e/​scenario/​node_config_test.go	Adds LocalDNS config-file parity assertions.

_{Review effort: Balanced}