[CI/Build] Skip spec decode tests using Triton backend

[zhewenl]

Purpose

More details in #27619.

EAGLE speculative decoding is failing on AMD GPUs with a HSA_STATUS_ERROR_MEMORY_APERTURE_VIOLATION error. The error occurs immediately when processing prompts starts, after successful CUDA graph capturing.
It can be reproduced with spec decode + EAGLE + Triton Attention Backend(default for AMD), example:

python3 offline_inference/spec_decode.py --test --method eagle --num_spec_tokens 3 --dataset-name hf --dataset-path philschmid/mt-bench --num-prompts 80 --temp 0 --top-p 1.0 --top-k -1 --tp 1 --enable-chunked-prefill --max-model-len 2048

Error Details

:0:rocdevice.cpp:3675: Callback: Queue 0x7f4db0300000 aborting with error:
HSA_STATUS_ERROR_MEMORY_APERTURE_VIOLATION: The agent attempted to access memory beyond the largest legal address. code: 0x29

(using a different backend could work: eg. ROCM_AITER_FA, ROCM_AITER_UNIFIED_ATTN, but TritonAttentionBackend is the default attention backend for AMD: gist:fb8bbb2cbde391905d86908ca4a46c02)

Test Plan

 pytest -v -s tests/v1/e2e/test_spec_decode.py::test_eagle_correctness

CI: https://buildkite.com/vllm/amd-ci/builds/814

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @zhewenl.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork