fix: Move keyword routing tests to e2e framework and validate matched_keywords

[szedan-rh]

• Relocate test files to e2e/testcases/ to trigger CI
• Add matched_keywords assertion in keyword routing E2E test
• Remove unused test types and old unit test directory

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[github-actions]

👥 vLLM Semantic Team Notification

The following members have been identified for the changed files in this PR and have been automatically assigned:

📁 e2e

Owners: @Xunzhuo
Files changed:

• e2e/testcases/keyword_routing.go
• e2e/testcases/testdata/keyword_routing_cases.json

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🎉 Thanks for your contributions!

This comment was automatically generated based on the OWNER files in the repository.

[szedan-rh]

@Xunzhuo / @srini-abhiram - PTAL

[Xunzhuo]

U should add the test case to the profiles, then make sure it appears in CI summary. Thanks