test(e2e): add control-plane plan/apply-workflow scenario

[Copilot]

• Create test/e2e/scenarios/control-plane/plan/apply-workflow/testdata/control-plane.yaml
• Create test/e2e/scenarios/control-plane/plan/apply-workflow/overlays/001-update/control-plane.yaml
• Create test/e2e/scenarios/control-plane/plan/apply-workflow/scenario.yaml
• Fix CI failure: template variables in assertion field keys are not interpolated — replace {{ .vars.cpRef }} with literal cp-plan-apply in both diff --plan assertion steps

[Copilot]

Pull request overview

Adds a new E2E scenario to cover the control-plane plan → save → diff --plan → apply --plan workflow, mirroring existing workflow coverage for other resource types so regressions in plan serialization/execution are detected.

Changes:

• Introduces a new control-plane plan/apply workflow scenario with create, update, and idempotency steps.
• Adds base declarative input for an initial control plane and an overlay to drive an UPDATE plan/apply cycle.
• Validates both JSON plan/apply outputs and text diff output for the saved plan file.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
test/e2e/scenarios/control-plane/plan/apply-workflow/testdata/control-plane.yaml	Base declarative control-plane config for the CREATE portion of the workflow.
test/e2e/scenarios/control-plane/plan/apply-workflow/overlays/001-update/control-plane.yaml	Overlay to update description/labels to force an UPDATE plan/apply cycle.
test/e2e/scenarios/control-plane/plan/apply-workflow/scenario.yaml	New scenario definition exercising plan-to-file, diff-from-file, apply-from-file, and idempotency assertions.

[rspurgeon]

@copilot evaluate the failure from this change in workflow 1533

=== RUN   Test_Scenarios/test/e2e/scenarios/control-plane/plan/apply-workflow/scenario.yaml
    scenarios_test.go:77: scenario failed: 001-plan-apply-create/001-diff-plan-text/assert-000: assertion mismatch; see /home/runner/work/kongctl/kongctl/.e2e-artifacts/24700394414-kongctl-acceptance-5/20260421-030959/tests/Test_Scenarios_test_e2e_scenarios_control-plane_plan_apply-workflow_scenario.yaml/steps/001-plan-apply-create/commands/001-diff-plan-text/assertions/assert-000

[Copilot]

@copilot evaluate the failure from this change in workflow 1533

=== RUN   Test_Scenarios/test/e2e/scenarios/control-plane/plan/apply-workflow/scenario.yaml

...

The failure was caused by using {{ .vars.cpRef }} in the JMESPath assertion field keys of the diff --plan steps — template variables are not interpolated in assertion keys. The observed diff output contained the literal ref cp-plan-apply, but the assertion was matching against the unexpanded template string.

Fixed in 7470b7b by replacing the template placeholders with their literal values (cp-plan-apply) in both diff --plan assertion steps, matching the pattern used in the event-gateway and portal/API scenarios.