[ROCm][CI] Prep Tests For Change To ROCM_ATTN As New Default Backend On ROCm (#36025)

Signed-off-by: Micah Williamson <micah.williamson@amd.com>

tests/models/multimodal/generation/test_common.py

@@ -173,6 +173,9 @@ VLM_TEST_SETTINGS = {
         marks=[
             pytest.mark.core_model,
         ],
+        vllm_runner_kwargs={"attention_backend": "TRITON_ATTN"}
+        if current_platform.is_rocm()
+        else {},
     ),
     "ultravox": VLMTestInfo(
         models=["fixie-ai/ultravox-v0_5-llama-3_2-1b"],