conformance: modify warmup from weighted two-pools test

[danehans]

What type of PR is this?

/kind flake

What this PR does / why we need it:

Modify the per-pod warmup loop in GatewayWeightedAcrossTwoInferencePools. The warmup used MakeRequestAndExpectEventuallyConsistentResponse (3 consecutive successes), which made requests targeting secondary endpoints probabilistic under 70/30 backendRef weighting and caused flakes.

Which issue(s) this PR fixes:

Fixes #2315

Does this PR introduce a user-facing change?:

NONE

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[danehans]

Summarizing 1 Failure:
  [FAIL] InferencePool when The Inference Extension is running [It] Should expose EPP metrics after generating traffic
  /home/prow/go/src/sigs.k8s.io/gateway-api-inference-extension/test/e2e/epp/e2e_test.go:489
Ran 2 of 4 Specs in 375.600 seconds
FAIL! -- 1 Passed | 1 Failed | 0 Pending | 2 Skipped
--- FAIL: TestAPIs (375.60s)
FAIL
FAIL	sigs.k8s.io/gateway-api-inference-extension/test/e2e/epp	375.656s
FAIL
make: *** [Makefile:158: test-e2e] Error 1

/retest

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: danehans, howardjohn

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• OWNERS [danehans]

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[zetxqx]

/lgtm

[kfswain]

/cherrypick release-1.3

[k8s-infra-cherrypick-robot]

@kfswain: #2316 failed to apply on top of branch "release-1.3":

Applying: conformance: remove warmup from GatewayWeightedAcrossTwoInferencePools test
Using index info to reconstruct a base tree...
M	conformance/tests/gateway_weighted_two_pools.go
Falling back to patching base and 3-way merge...
Auto-merging conformance/tests/gateway_weighted_two_pools.go
CONFLICT (content): Merge conflict in conformance/tests/gateway_weighted_two_pools.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
Patch failed at 0001 conformance: remove warmup from GatewayWeightedAcrossTwoInferencePools test

Details

In response to this:

/cherrypick release-1.3

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