[CI] Optimize test execution with single-GPU parallelism

[EmmonsCurse]

Motivation

Current unittest execution runs mostly in a sequential manner, leading to low GPU utilization and long CI turnaround time.
In addition, when tests fail, logs are scattered and not easy to locate, which increases debugging cost.

Modifications

• Introduce single-GPU parallel execution by splitting independent tests into multiple shards
• Classify tests into multi-GPU and single-GPU to ensure correct scheduling
• Execute multi-GPU tests sequentially to avoid resource conflicts
• Isolate log directories per test and collect logs on failure
• Package and upload logs for easier debugging and traceability

Usage or Command

N/A

Accuracy Tests

N/A

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
  • You can add new tags based on the PR content, but the semantics must be clear.
• Format your code, run pre-commit before commit.
• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

[EmmonsCurse]

/skip-ci ci_iluvatar
/skip-ci ci_hpu
/skip-ci build_xpu
/skip-ci gpu_4cards_test
/skip-ci pre_ce_test
/skip-ci stable_test
/skip-ci base_test
/skip-ci logprob_test

[paddle-bot]

Thanks for your contribution!

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (develop@3651113). Learn more about missing BASE report.

Additional details and impacted files

@@            Coverage Diff             @@
##             develop    #7085   +/-   ##
==========================================
  Coverage           ?   72.34%           
==========================================
  Files              ?      376           
  Lines              ?    52766           
  Branches           ?     8236           
==========================================
  Hits               ?    38172           
  Misses             ?    11961           
  Partials           ?     2633           

Flag	Coverage Δ
GPU	72.34% <ø> (?)

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