[main][bugfix] Fixed the problem of speculative decoding in FULL mode (#7148)

### What this PR does / why we need it?

Fixed the error of speculative decoding in FULL mode when `num_spec + 1`
not in `cudagraph_capture_sizes`.

Now, we can run speculative decoding in FULL mode, but with drafter as
eager.

It depends on https://github.com/vllm-project/vllm-ascend/pull/7144 .

### Does this PR introduce _any_ user-facing change?

N/A

### How was this patch tested?

Test code is shown as below:

```python
prompts = [
    "1.Who are you?",
    "2. Who are you?",
]

sampling_params = SamplingParams(temperature=0.0, top_p=0.95, top_k=40, max_tokens=200)
llm = LLM(
    model="/home/some-model/Meta-Llama-3.1-8B-Instruct",
    tensor_parallel_size=1,
    max_num_seqs=32,
    # enforce_eager=True,
    disable_log_stats=False,
    distributed_executor_backend="mp",
    gpu_memory_utilization=0.7,
    async_scheduling=True,

    speculative_config={
        "enforce_eager": True,
        "model": "/home/some-model/EAGLE3-LLaMA3.1-Instruct-8B",
        "disable_padded_drafter_batch": False,
        "method": "eagle3",
        "num_speculative_tokens": 2,
    },
    
    compilation_config={
        "cudagraph_mode": "FULL",
        "cudagraph_num_of_warmups": 1,
    },

    max_model_len=4096, 
    enable_prefix_caching=False,
)

outputs = llm.generate(prompts, sampling_params)
```

The result before:

```text
   File "/vllm-workspace/vllm/vllm/v1/cudagraph_dispatcher.py", line 140, in _create_padded_batch_descriptor
     assert num_tokens_padded % uniform_decode_query_len == 0
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 AssertionError
```

The result after:

```text
--------------------------------------------------
total_num_output_tokens: 400
num_drafts: 249
num_draft_tokens: 498
num_accepted_tokens: 149
mean acceptance length: 1.60
--------------------------------------------------
acceptance at token 0: 0.43
acceptance at token 1: 0.17
```

- vLLM version: v0.16.0
- vLLM main:
4034c3d32e

Signed-off-by: drslark <slarksblood@qq.com>

vllm_ascend/patch/__init__.py

@@ -438,3 +438,17 @@
 #       patch Qwen3_5GatedDeltaNet._forward_core to use triton ops like `fused_recurrent_gated_delta_rule`.
 #    Future Plan:
 #       Remove this patch when all ops in _forward_core support both Qwen3_5 and Qwen3Next.
+#
+# ** 20. File: worker/patch_cudagraph.py**
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+#   1. `vllm.v1.cudagraph_dispatcher.CudagraphDispatcher._create_padded_batch_descriptor`
+#    Why:
+#       vllm's FULL mode will cause error, we use a patch to avoid it.
+#       After that, FULL can be enable now.
+#    How：
+#       Dynamically replace the `_create_padded_batch_descriptor` function at runtime,
+#       and change the condition of if.
+#    Related PR (if no, explain why):
+#       https://github.com/vllm-project/vllm/pull/34880
+#    Future Plan:
+#       Remove this patch when vLLM merges the PR.