[Bugfix][CI]Add qwen3Next MTP+Full Decode (#6047)

### What this PR does / why we need it?
Fix a bug in the repo and add a test case for MTP + Full Decode Only +
Qwen3Next.
The _build_dummy_attn_metadata function in NPUModelRunner seems losed a
query_star_loc.copy_to_gpu operation, which will lead to difference
between query_start_loc and query_start_loc_cpu, and they are required
to be same in MTP + Full Decode Only + Qwen3Next case.

Before this pr:
`self.query_start_loc = [0, 0, 0, 0, ... , 0]
self.query_start_loc_cpu = [0, 2, 4, 6, ... ,128]`

### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?

- vLLM version: v0.13.0
- vLLM main:
d68209402d

---------

Signed-off-by: SunnyLee219 <3294305115@qq.com>

tests/e2e/multicard/4-cards/spec_decode/test_mtp_qwen3_next.py

@@ -152,3 +152,37 @@ def test_qwen3_next_mtp_correctness_tp4(model_name: str,
     # Upon failure, inspect the outputs to check for inaccuracy.
     assert matches > int(0.66 * len(ref_outputs))
     cleanup_dist_env_and_memory()
+
+
+@pytest.mark.parametrize("model_name", MODELS)
+@pytest.mark.parametrize("num_speculative_tokens", [1])
+def test_qwen3_next_mtp_full_decode(model_name: str,
+                                        num_speculative_tokens: int):
+    example_prompts = [
+        "Hello, my name is",
+        "The president of the United States is",
+        "The capital of France is",
+        "The future of AI is",
+    ]
+
+    max_tokens = 20
+    '''
+    Compare the outputs of a original LLM and a speculative LLM
+    should be the same when using mtp speculative decoding.
+    '''
+    with VllmRunner(model_name,
+                    tensor_parallel_size=4,
+                    max_model_len=4096,
+                    gpu_memory_utilization=0.8,
+                    distributed_executor_backend="mp",
+                    speculative_config={
+                        "method": "qwen3_next_mtp",
+                        "num_speculative_tokens": num_speculative_tokens,
+                    },
+                    compilation_config=CompilationConfig(
+                        cudagraph_mode="FULL_DECODE_ONLY",
+                        cudagraph_capture_sizes=[4])) as llm:
+        outputs = llm.generate_greedy(example_prompts, max_tokens)
+        print(outputs)
+    del llm
+    cleanup_dist_env_and_memory()

vllm_ascend/patch/worker/patch_qwen3_next.py

@@ -217,13 +217,8 @@ class AscendQwen3Next_GatedDeltaNet(nn.Module, MambaBase):
             mixed_qkv_non_spec)
 
         if attn_metadata.num_prefills > 0 or spec_sequence_masks is not None:
-            is_cuda_graph = forward_context.cudagraph_runtime_mode != CUDAGraphMode.NONE
-            if (is_cuda_graph):
-                g, beta = fused_gdn_gating_patch(self.A_log, a, b,
-                                                 self.dt_bias)
-            else:
-                g, beta = fused_gdn_gating(self.A_log, a, b, self.dt_bias)
-
+            g, beta = fused_gdn_gating_patch(self.A_log, a, b,
+                                                self.dt_bias)
             if spec_sequence_masks is not None:
                 if attn_metadata.num_prefills == 0 and attn_metadata.num_decodes == 0:
                     g_spec = g