test(clusterapi): assert the EKS ownership guard refuses Start, not only Stop

[devantler]

🤖 Generated by the Agentic Engineer

Evidence

Start and Stop both route through runLifecycleAction → runGuardedProvisioner
(pkg/cli/clusterapi/local_service.go:840), so both carry the EKS ownership guard. The test suite
covers that refusal for Stop only — TestStopEKSRefusesWhenOwnershipCannotBeVerified — with no
Start equivalent.

Measured while validating #6203: ablating the guard flips 9 tests, none of which exercise Start.

Affected audience and impact

No user-visible gap today: the protection is shared by construction, so Start is guarded. The risk
is regression-shaped — a future refactor that gives Start its own path (or reorders the guard for
one action) would lose the ownership check on Start with the suite still fully green.

Expected behaviour

The guard's refusal is asserted for every guarded mutation, not just delete and stop.

Acceptance criteria

• A Start arm asserts the mutation is refused when ownership cannot be verified, mirroring
  TestStopEKSRefusesWhenOwnershipCannotBeVerified.
• The new arm fails when the guard is ablated (a passing test that survives the ablation is proving
  nothing).

Rough size

Small — one test arm in pkg/cli/clusterapi.

[coderabbitai]

🔗 Related PRs

#5917 - feat(cluster): reject start/stop on unmanaged clusters with a clear error [merged]
#5950 - feat(cluster): reject delete on unmanaged clusters [merged]
#6333 - feat(eks): reconcile AWS load balancer controller opt-in [merged]
#6385 - fix(clusterapi): bind local API EKS lifecycle actions to the creating region [merged]
#6434 - fix(clusterapi): verify EKS ownership before local API lifecycle actions [merged]

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[devantler]

🤖 Generated by the Agentic Engineer

Duplicate of #6478 — same issue filed twice, 7 seconds apart (13:14:09Z and 13:14:16Z) with byte-identical bodies, so the create was evidently retried. Closing this one and keeping #6478, which is the copy that carries the Chore Issue Type.

No content is lost: the two bodies are identical.