[CI]: Add Qwen3.5 27B/35B/397B Workflow

[sammysun0711]

Motivation

Add model accuracy and performance benchmark CI on Qwen3.5 v0.5.15 branch for following models:

• Qwen3.5 27B PTPC FP8
• Qwen3.5 35B A3B PTPC FP8
• Qwen3.5 397B A17B PTPC FP8

Modifications

Accuracy Tests

Model	GSM8K
Qwen3.5 27B PTPC FP8	0.855
Qwen3.5 35B A3B PTPC FP8	0.855
Qwen3.5 397B A17B PTPC FP8	0.955

Speed Tests and Profiling

ISL 8000 / OSL 500 / Concurrency 1 w/o dflash

Model	TP	TTFT	TPOT
Qwen3.5 27B PTPC FP8	1	1436.36	12.91
Qwen3.5 35B A3B PTPC FP8	4	182.50	3.87
Qwen3.5 397B A17B PTPC FP8	8	392.00	10.70

Checklist

• Format your code according to the Format code with pre-commit.
• Add unit tests according to the Run and add unit tests.
• Update documentation according to Write documentations.
• Provide accuracy and speed benchmark results according to Test the accuracy and Benchmark the speed.
• Follow the SGLang code style guidance.

Review and Merge Process

1. Ping Merge Oncalls to start the process. See the PR Merge Process.
2. Get approvals from CODEOWNERS and other reviewers.
3. Trigger CI tests with comments or contact authorized users to do so.
   • Common commands include /tag-and-rerun-ci, /tag-run-ci-label, /rerun-failed-ci
4. After green CI and required approvals, ask Merge Oncalls or people with Write permission to merge the PR.

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CI States

Latest PR Test (Base): ❌ Missing run-ci label -- add it to run CI tests.
Latest PR Test (Extra): ❌ Blocked -- run-ci is required first.