[BugFix] Fix flashcomm_v1 when engine v0 (#1859)

### What this PR does / why we need it?
Fix missing attn_state attribute bug in engine_v0 scenario when enabling
Flashcomm_v1.

### Does this PR introduce _any_ user-facing change?
No.

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

Signed-off-by: rjg-lyh <1318825571@qq.com>

Author: rjg-lyh

vllm_ascend/models/qwen2.py

@@ -3,6 +3,7 @@
 
 import torch
 import torch.nn.functional as F
+import vllm.envs as envs
 from torch import nn
 from transformers import Qwen2Config
 from vllm.compilation.decorators import support_torch_compile
@@ -154,6 +155,7 @@ def forward(
         flashcomm_v1_enabled = False
         attn_metadata = get_forward_context().attn_metadata
         if ascend_envs.VLLM_ASCEND_ENABLE_FLASHCOMM == 1 and \
+            envs.VLLM_USE_V1 and \
             attn_metadata is not None and \
             attn_metadata.attn_state != AscendAttentionState.DecodeOnly:
             flashcomm_v1_enabled = True