[Misc] Remove redundant imported envs, using envs_ascend instead (#2193)

### What this PR does / why we need it?
Remove redundant imported `envs`, using `envs_ascend` instead.

```python
import vllm.envs as envs_vllm
import vllm_ascend.envs as envs_ascend
```

- vLLM version: v0.10.0
- vLLM main:
71683ca6f6

---------

Signed-off-by: shen-shanshan <467638484@qq.com>

vllm_ascend/platform.py

@@ -20,7 +20,7 @@ from datetime import timedelta
 from typing import TYPE_CHECKING, Optional, Tuple
 
 import torch
-import vllm.envs as envs
+import vllm.envs as envs_vllm
 from torch.distributed import ProcessGroup
 from torch.distributed.distributed_c10d import PrefixStore
 from vllm.logger import logger
@@ -116,7 +116,7 @@ class NPUPlatform(Platform):
 
     @classmethod
     def check_and_update_config(cls, vllm_config: VllmConfig) -> None:
-        if not envs.VLLM_USE_V1:
+        if not envs_vllm.VLLM_USE_V1:
             raise ValueError("vLLM Ascend does not support V0 engine.")
         # initialize ascend config from vllm additional_config
         ascend_config = init_ascend_config(vllm_config)