Add kubernetai axfr tests

[davidmccormick]

This PR builds upon #157 to add kubernetai AXFR integration tests.

The kubernetai tests should fail until AXFR is properly supported in the plugin:

=== RUN   TestAXFR
=== RUN   TestAXFR/matches_stanza_1/test-4.svc.cluster.local._AXFR
    axfr_test.go:187: expected 1 query attempt, observed 0
    axfr_test.go:196: coredns log: .:53
        CoreDNS-1.11.3
        linux/arm64, go1.23.1, ce45312
        [INFO] 172.17.0.1:37727 - 13103 "AXFR IN test-4.svc.cluster.local. tcp 65 false 65535" - - 0 0.000046625s
=== RUN   TestAXFR/matches_stanza_2/test-5.svc.cluster.local._AXFR
    axfr_test.go:187: expected 1 query attempt, observed 0
    axfr_test.go:196: coredns log: .:53
        CoreDNS-1.11.3
        linux/arm64, go1.23.1, ce45312
        [INFO] 172.17.0.1:36319 - 63827 "AXFR IN test-5.svc.cluster.local. tcp 65 false 65535" - - 0 0.0000605s
=== RUN   TestAXFR/matches_first_stanza/cluster.local._AXFR
    axfr_test.go:187: expected 1 query attempt, observed 0
    axfr_test.go:196: coredns log: .:53
        CoreDNS-1.11.3
        linux/arm64, go1.23.1, ce45312
        [INFO] 172.17.0.1:57837 - 14074 "AXFR IN cluster.local. tcp 54 false 65535" - - 0 0.00003625s
--- FAIL: TestAXFR (9.17s)
    --- FAIL: TestAXFR/matches_stanza_1/test-4.svc.cluster.local._AXFR (3.09s)
    --- FAIL: TestAXFR/matches_stanza_2/test-5.svc.cluster.local._AXFR (3.11s)
    --- FAIL: TestAXFR/matches_first_stanza/cluster.local._AXFR (2.97s)
FAIL
FAIL	github.com/coredns/ci/test/kubernetai	24.938s
FAIL

Support is added in coredns/kubernetai#66. Manual running of the tests against this PR - the tests pass:

cd $GOPATH/src/github.com/coredns/ci && go mod tidy && go test -v ./test/kubernetai/... --run=TestAXFR                                                                                                                                     ✔  16:03:36 
=== RUN   TestAXFR
=== RUN   TestAXFR/matches_stanza_1/test-4.svc.cluster.local._AXFR
=== RUN   TestAXFR/matches_stanza_2/test-5.svc.cluster.local._AXFR
=== RUN   TestAXFR/matches_first_stanza/cluster.local._AXFR
--- PASS: TestAXFR (8.59s)
    --- PASS: TestAXFR/matches_stanza_1/test-4.svc.cluster.local._AXFR (2.50s)
    --- PASS: TestAXFR/matches_stanza_2/test-5.svc.cluster.local._AXFR (3.01s)
    --- PASS: TestAXFR/matches_first_stanza/cluster.local._AXFR (3.08s)
PASS
ok      github.com/coredns/ci/test/kubernetai    9.297s

[davidmccormick]

This PR fixes the metadata_edns0 plugin failure coredns/metadata_edns0#22

[davidmccormick]

#157 should be merged before this one as it add's passing AXFR tests for the kubernetes plugin.