[Misc] DeepEPHighThroughtput - Enable Inductor pass

[varun-sundar-rabindranath]

Purpose

DeepEPHighThroughput All2All kernels + Torch Inductor pass yielded incorrect results for deepseek-v2-lite models. The Inductor pass was disabled as a result. This PR enables it again as we don't see any issues now.

Test Plan

e2e tests:
server command : VLLM_ALL2ALL_BACKEND="deepep_high_throughput" VLLM_USE_DEEP_GEMM=1 canhazgpu run -g 2 -- vllm serve $MODEL --trust-remote-code --enable-expert-parallel --data-parallel-size 2 --port 9010 --no-enable-prefix-caching
lm_eval command : lm_eval --model local-completions --tasks gsm8k --model_args model=$MODEL,base_url=http://127.0.0.1:9010/v1/completions,num_concurrent=30,max_retries=3 --limit 100

Test Result

Model = deepseek-ai/DeepSeek-V2-Lite

|Tasks|Version|     Filter     |n-shot|  Metric   |   |Value|   |Stderr|
|-----|------:|----------------|-----:|-----------|---|----:|---|-----:|
|gsm8k|      3|flexible-extract|     5|exact_match|↑  | 0.29|±  |0.0456|
|     |       |strict-match    |     5|exact_match|↑  | 0.29|±  |0.0456|

Model = Qwen/Qwen3-30B-A3B-FP8

|Tasks|Version|     Filter     |n-shot|  Metric   |   |Value|   |Stderr|
|-----|------:|----------------|-----:|-----------|---|----:|---|-----:|
|gsm8k|      3|flexible-extract|     5|exact_match|↑  | 0.85|±  |0.0359|
|     |       |strict-match    |     5|exact_match|↑  | 0.94|±  |0.0239|

Results are similar to what we see on main

(Optional) Documentation Update

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[gemini-code-assist]

Code Review

This pull request re-enables the Torch Inductor pass for the DeepEPHighThroughput backend. This feature was previously disabled due to correctness issues with specific models, and the change removes the corresponding workaround. The provided test results for deepseek-v2-lite and Qwen/Qwen3-30B-A3B-FP8 support the claim that the underlying issue has been resolved. The change is straightforward and improves both performance and code maintainability. I see no issues with this change.

[varun-sundar-rabindranath]

cc @ProExpertProg @zou3519