[CI] Pooling models mteb test disable enforce_eager

[noooop]

Purpose

Related to #22862

• [Bug]: Numerics of Embedding Models #22862 (flaky test finded)
• [CI] Pooling models mteb test uses enforce_eager #22878 (uses enforce_eager)
• [CI] Accelerate mteb test by setting SentenceTransformers mteb score to a constant #24088 (Since [CI] Pooling models mteb test uses enforce_eager #22878 Pooling models mteb test uses enforce_eager, mteb_test_embed_models has become less (never) flaky.)
• [CI] Split mteb test from Language Models Test #24634

Let's re-disable enforce_eager and check if the flaky test has been fixed.

• If it has already been fixed, everyone is happy.
• If it hasn't been fixed yet, error logs can help experts debug during the new release cycle.

The mteb test has been separated from Language Models Test in #24634, so the Nightly Test keeps failing, it won't confuse anyone.

cc @DarkLight1337 @robertgshaw2-redhat @zou3519

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request aims to re-enable optimized code paths for certain tests by removing enforce_eager=True, with the goal of verifying a fix for a flaky test. The changes in tests/models/language/pooling_mteb_test/mteb_utils.py align perfectly with this objective. However, a similar change in tests/models/language/generation_ppl_test/ppl_utils.py seems out of scope and could potentially introduce instability in a different test suite. My review includes a comment highlighting this concern.

[noooop]

https://buildkite.com/vllm/ci/builds/34315/steps/canvas?sid=0199cc47-93cd-48de-9a15-04250b1a3b55

[2025-10-10T04:42:04Z] FAILED models/language/pooling_mteb_test/test_bge_reranker_v2_gemma.py::test_rerank_models_mteb[model_info0] - RuntimeError: Engine core initialization failed. See root cause above. Failed core proc(s): {}
[2025-10-10T04:42:04Z] FAILED models/language/pooling_mteb_test/test_jina.py::test_embed_models_mteb[model_info0] - vllm.v1.engine.exceptions.EngineDeadError: EngineCore encountered an issue. See stack trace (above) for the root cause.
[2025-10-10T04:42:04Z] FAILED models/language/pooling_mteb_test/test_st_projector.py::test_embed_models_mteb[model_info1] - AssertionError

Can be reproduced locally

@Isotr0py Could you please help to do further investigation.