feat(conformance): Add HTTPRouteMultipleGatewaysDifferentPools test

[SinaChavoshi]

This PR introduces a new conformance test, HTTPRouteMultipleGatewaysDifferentPools, which validates a scenario where two distinct HTTPRoute resources, parented by different Gateway resources, successfully reference and route traffic to separate InferencePool backends.

local run results: ( Ran on commit 1451a90 )

go test -v ./conformance -args -debug     -gateway-class gke-l7-regional-external-managed     -cleanup-base-resources=false     -run-test HTTPRouteMultipleGatewaysDifferentPools
...
    apply.go:283: 2025-05-28T19:00:01.843473338Z: Deleting multi-gw-primary-backend-deployment Deployment
=== RUN   TestConformance/InferencePoolAccepted
    conformance.go:68: Skipping InferencePoolAccepted: test explicitly skipped
=== RUN   TestConformance/InferencePoolResolvedRefsCondition
    conformance.go:68: Skipping InferencePoolResolvedRefsCondition: test explicitly skipped
--- PASS: TestConformance (13.43s)
    --- SKIP: TestConformance/HTTPRouteInvalidInferencePoolRef (0.00s)
    --- PASS: TestConformance/HTTPRouteMultipleGatewaysDifferentPools (10.84s)
        --- PASS: TestConformance/HTTPRouteMultipleGatewaysDifferentPools/Primary_HTTPRoute,_InferencePool,_and_Gateway_path:_verify_status_and_traffic (6.82s)
        --- PASS: TestConformance/HTTPRouteMultipleGatewaysDifferentPools/Secondary_HTTPRoute,_InferencePool,_and_Gateway_path:_verify_status_and_traffic (1.48s)
    --- SKIP: TestConformance/InferencePoolAccepted (0.00s)
    --- SKIP: TestConformance/InferencePoolResolvedRefsCondition (0.00s)
PASS
ok      sigs.k8s.io/gateway-api-inference-extension/conformance 13.635s

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[k8s-ci-robot]

Hi @SinaChavoshi. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[spencerhance]

/cc

[spencerhance]

/lgtm

[spencerhance]

/lgtm

[ahg-g]

/ok-to-test

[k8s-ci-robot]

New changes are detected. LGTM label has been removed.

[robscott]

Thanks @SinaChavoshi! A couple tiny nits, otherwise LGTM.

[robscott]

Sorry, just adding a couple tiny nits as I've been thinking more broadly about how this will fit in with the rest of the conformance tests.

[SinaChavoshi]

@danehans @nirrozenbaum Any chance I could get another review / approval on this PR.

[SinaChavoshi]

/assign @danehans

[danehans]

@SinaChavoshi now that #866 merged, this PR needs a rebase.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: robscott, SinaChavoshi, spencerhance
Once this PR has been reviewed and has the lgtm label, please ask for approval from danehans. For more information see the Code Review Process.

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[LiorLieberman]

/cc

[LiorLieberman]

I am pretty sure I saw this code in a different PR, could that be true?

[danehans]

The conformance test suite requires either a mock EPP or EPP + https://github.com/llm-d/llm-d-inference-sim.

See #893 for additional details.

/hold