[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/worker/model_runner_v1.py

@@ -71,7 +71,6 @@ from vllm.v1.worker.utils import (bind_kv_cache, gather_mm_placeholders,
                                   sanity_check_mm_encoder_outputs,
                                   scatter_mm_placeholders)
 
-from vllm_ascend import envs
 from vllm_ascend.ascend_config import get_ascend_config
 from vllm_ascend.ascend_forward_context import set_ascend_forward_context
 from vllm_ascend.attention.attention_mask import AttentionMaskBuilder
@@ -172,7 +171,7 @@ class NPUModelRunner(LoRAModelRunnerMixin):
         self.dp_rank = vllm_config.parallel_config.data_parallel_rank
         self.device = device
         self.dtype = self.model_config.dtype
-        if envs.VLLM_ASCEND_ENABLE_TOPK_TOPP_OPTIMIZATION:
+        if envs_ascend.VLLM_ASCEND_ENABLE_TOPK_TOPP_OPTIMIZATION:
             # TODO: drop the env config to use ascend sampler by default
             from vllm_ascend.sample.sampler import AscendSampler