[Bugfix] Fix aclgraph not enabled by default (#2590)

### What this PR does / why we need it?
As vllm will set `cudagraph_mode` to `NONE` before
`check_and_update_config` in post init of `VllmConfig`
(5da4f5d857/vllm/config/__init__.py (L3630)),
we always have `cudagraph_mode` isn't `None`, thus we must remove this
check and add it when the related adaption in vllm is done.

part of https://github.com/vllm-project/vllm-ascend/pull/2577, will add
the e2e test on applying reply after the CI refactor is done

### How was this patch tested?
CI passed with existing test.

- vLLM version: v0.10.1.1
- vLLM main:
f48a9af892

Signed-off-by: MengqingCao <cmq0113@163.com>

tests/ut/test_platform.py

@@ -3,6 +3,7 @@ import unittest
 from datetime import timedelta
 from unittest.mock import MagicMock, patch
 
+import pytest
 import torch
 from torch.distributed import ProcessGroup
 from torch.distributed.distributed_c10d import PrefixStore
@@ -318,6 +319,8 @@ class TestNPUPlatform(TestBase):
                 CUDAGraphMode.NONE,
             )
 
+    @pytest.mark.skip(
+        "Revert me when vllm support setting cudagraph_mode on oot platform")
     @patch("vllm_ascend.utils.is_310p", return_value=False)
     @patch("vllm_ascend.ascend_config.check_ascend_config")
     @patch("vllm_ascend.ascend_config.init_ascend_config")