Add Kubernetes API coverage test consuming traces

[AwesomePatrol]

It pulls a file from testdata with traces collected by Jaeger and then iterates over them in order to group them into those which use the contract interface, are known (and usually valid) uses outside of it. Later it can further analyze the parameters used over the run of Kubernetes conformance tests.

It requires patched Kubernetes
with:
AwesomePatrol/kubernetes@5a18a66 or at:
https://github.com/AwesomePatrol/kubernetes/tree/add-kubernetes-etcd-contract-tracker

Example result:

=== RUN   TestInterfaceUse
=== RUN   TestInterfaceUse/all_conformance_traces_2025-06-16a.json
=== RUN   TestInterfaceUse/all_conformance_traces_2025-06-16a.json/interface_bypass
    coverage_test.go:61: Traces which did not go through the interface: 4489 / 44064
    coverage_test.go:93: contract bypass count by operation: map[etcdserverpb.KV/Compact:11 etcdserverpb.Lease/LeaseGrant:318 etcdserverpb.Maintenance/Status:84 etcdserverpb.Watch/Watch:23]
=== RUN   TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed
=== RUN   TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/Get_kubernetesEtcdContract
    coverage_test.go:117: Found 23231 traces matching Get kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:0 unset:23231]
=== RUN   TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/OptimisticPut_kubernetesEtcdContract
    coverage_test.go:117: Found 13576 traces matching OptimisticPut kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:9808 unset:3768]
=== RUN   TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/OptimisticDelete_kubernetesEtcdContract
    coverage_test.go:117: Found 1430 traces matching OptimisticDelete kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:1430 unset:0]
=== RUN   TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/List_kubernetesEtcdContract
    coverage_test.go:117: Found 6726 traces matching List kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:5641 unset:1085]
=== RUN   TestInterfaceUse/all_e2e_traces_2025-06-17a.json
    coverage_test.go:51: WARNING: some traces are present in Etcd only: 1004 > 0
=== RUN   TestInterfaceUse/all_e2e_traces_2025-06-17a.json/interface_bypass
    coverage_test.go:61: Traces which did not go through the interface: 6417 / 40802
    coverage_test.go:93: contract bypass count by operation: map[etcdserverpb.KV/Compact:14 etcdserverpb.Lease/LeaseGrant:454 etcdserverpb.Maintenance/Status:122 etcdserverpb.Watch/Watch:6]
=== RUN   TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed
=== RUN   TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/OptimisticPut_kubernetesEtcdContract
    coverage_test.go:117: Found 12557 traces matching OptimisticPut kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:10765 unset:1792]
=== RUN   TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/OptimisticDelete_kubernetesEtcdContract
    coverage_test.go:117: Found 906 traces matching OptimisticDelete kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:906 unset:0]
=== RUN   TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/List_kubernetesEtcdContract
    coverage_test.go:117: Found 3903 traces matching List kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:2864 unset:1039]
=== RUN   TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/Get_kubernetesEtcdContract
    coverage_test.go:117: Found 17610 traces matching Get kubernetesEtcdContract operation
    coverage_test.go:127: Distribution of revision values: map[missing:0 set:0 unset:17610]
--- PASS: TestInterfaceUse (12.92s)
    --- PASS: TestInterfaceUse/all_conformance_traces_2025-06-16a.json (7.11s)
        --- PASS: TestInterfaceUse/all_conformance_traces_2025-06-16a.json/interface_bypass (0.01s)
        --- PASS: TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed (0.03s)
            --- PASS: TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/Get_kubernetesEtcdContract (0.01s)
            --- PASS: TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/OptimisticPut_kubernetesEtcdContract (0.01s)
            --- PASS: TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/OptimisticDelete_kubernetesEtcdContract (0.01s)
            --- PASS: TestInterfaceUse/all_conformance_traces_2025-06-16a.json/contract_methods_set_rev_when_needed/List_kubernetesEtcdContract (0.01s)
    --- PASS: TestInterfaceUse/all_e2e_traces_2025-06-17a.json (5.81s)
        --- PASS: TestInterfaceUse/all_e2e_traces_2025-06-17a.json/interface_bypass (0.01s)
        --- PASS: TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed (0.03s)
            --- PASS: TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/OptimisticPut_kubernetesEtcdContract (0.01s)
            --- PASS: TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/OptimisticDelete_kubernetesEtcdContract (0.00s)
            --- PASS: TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/List_kubernetesEtcdContract (0.01s)
            --- PASS: TestInterfaceUse/all_e2e_traces_2025-06-17a.json/contract_methods_set_rev_when_needed/Get_kubernetesEtcdContract (0.01s)
PASS
ok      go.etcd.io/etcd/tests/v3/robustness/coverage    12.950s

There are some TODO comments left in the code. More information in the related issue.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[k8s-ci-robot]

Hi @AwesomePatrol. Thanks for your PR.

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