[CI] Split pooling from entrypoints Test

[noooop]

Purpose

refactoring following #22992

Split pooling from entrypoints Test to Entrypoints Integration Test (Pooling) ~19 minutes

cc @DarkLight1337 @maxdebayser

Test Plan

pytest -v -s entrypoints/pooling

Test Result

keep ci green

Known Issues

entrypoints-integration-test-api-server still takes a long time ~1 hour, 49 minutes, we may need to split it further

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[gemini-code-assist]

Code Review

This pull request refactors the CI pipeline by splitting the pooling tests into a dedicated job. The file moves and import path updates are correct and improve the project structure. However, I've identified a potential issue with the new CI job's configuration: the timeout is set to a very high value of 130 minutes, which could impact CI performance and cost. I recommend reviewing this setting.