Add test for Radix cache variants

[Edenzzzz]

Motivation

Add test to ensure radix cache functionalities are complete and runnable after refactors such as #3986

Modifications

Checklist

• Format your code according to the Code Formatting with Pre-Commit.
• Add unit tests as outlined in the Running Unit Tests.
• Update documentation / docstrings / example tutorials as needed, according to Writing Documentation.
• Provide throughput / latency benchmark results and accuracy evaluation results as needed, according to Benchmark and Profiling and Accuracy Results.
• For reviewers: If you haven't made any contributions to this PR and are only assisting with merging the main branch, please remove yourself as a co-author when merging the PR.
• Please feel free to join our Slack channel at https://slack.sglang.ai to discuss your PR.

[zhyncs]

Can you check all the code?

[zhyncs]

Also please add test for it.

[zhyncs]

This change is wrong https://github.com/sgl-project/sglang/actions/runs/13691250535/job/38284792114?pr=4125 Can you test locally by yourself?

[Edenzzzz]

@zhyncs Sure, I will add a test with @xihuai18 that tests if different args for the cache are runnable

[Edenzzzz]

@zhyncs Should we also test evict? It seems to happen at very high request rates, not sure how many requests are needed

[zhaochenyang20]

@Edenzzzz I am good with the tests. But, add it in the run suites. @Edenzzzz

[Edenzzzz]

@zhaochenyang20 Added

[github-actions]

This pull request has been automatically closed due to inactivity. Please feel free to reopen it if needed.