ci: track test flavor in per-test baseline and rename job to Track Test Duration

[hsuan-lun-chiang]

Description

This PR addresses hardware-dependent test duration noise in the Per-Test Baseline comparison and updates workflow job naming.

Problem & Context

Previously, per_test_baseline.json tracked test durations using un-flavored test names. When a test ran on multiple hardware platforms with different execution times (e.g., QKClipMLATest.test_mla_dot_product_integration taking 0.94s on CPU vs 15.99s on GPU), baseline comparison falsely flagged regressions when comparing across hardware types.

Solution

1. Track Hardware Test Flavor: Baseline keys in per_test_baseline.json are now formatted as flavor::test_name (e.g., gpu-unit::tests.unit.qk_clip_test...), isolating durations for each hardware flavor.
2. Legacy Key Clean-up: Automatically purges un-flavored legacy baseline keys when initializing new_per_test_baseline.json.
3. Rename Job & Workflow: Updated job name from Track Test Performance to Track Test Duration in track_performance.yml and ci_pipeline.yml.
4. Unit Tests: Added tests/utils/process_test_results_test.py to verify per-flavor baseline isolation and regression checking.

Tests

Ran local unit tests and pre-commit hooks:

python3 tests/utils/process_test_results_test.py
pre-commit run --files tests/utils/process_test_results.py tests/utils/process_test_results_test.py .github/workflows/track_performance.yml .github/workflows/ci_pipeline.yml

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• I have performed a self-review of my code. For an optional AI review, add the gemini-review label.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run end-to-end tests tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[gemini-code-assist]

Caution

The consumer version of Gemini Code Assist on GitHub has been sunset. All code review activity has officially ceased.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!