Default enable MLAPO (#5952)

### What this PR does / why we need it?
1) Default enable MLAPO for deepseek MLA Attention W8A8 models on PD
disagregation D Instance, for example: DeepSeekV3-W8A8,
DeepSeek-R1-W8A8.
2) Default enable MLAPO for DeepSeek SFA Attention W8A8 models,
currently is DeepSeek-V3.2-W8A8.

### Does this PR introduce _any_ user-facing change?
Don't need use manully to VLLM_ASCEND_ENABLE_MLAPO=1, to enable MLAPO
feature for deepseek w8a8 model

The effect of enabling MLAPO SFA model deployed on a single A3 Node:
Test
with:tests/e2e/nightly/single_node/models/test_deepseek_v3_2_exp_w8a8.py
dataset: gsm8k-lite，without set MTP, FULL GRAPH, has 19% promote：
未默认开启 MLAPO 时：
├─────────────────────────┤
│                TTFT                      │ 14055.8836 ms   │
├─────────────────────────┤
│                ITL                         │ 66.8171 ms.          │
├─────────────────────────┤
│ Output Token Throughput  │ 104.9105 token/s │
├─────────────────────────┤
默认开启 MLAPO 时：
├─────────────────────────┤
│                TTFT                      │ 3753.1547 ms   │
├─────────────────────────┤
│                ITL.                        │ 61.4236  ms.       │
├─────────────────────────┤
│ Output Token Throughput  │ 125.2075 token/s│
├─────────────────────────┤

- vLLM version: v0.13.0
- vLLM main:
2c24bc6996

---------

Signed-off-by: leo-pony <nengjunma@outlook.com>

vllm_ascend/attention/utils.py

@@ -9,6 +9,7 @@ from vllm.distributed.kv_transfer import get_kv_transfer_group, has_kv_transfer_
 from vllm.forward_context import ForwardContext, get_forward_context
 from vllm.v1.attention.backends.utils import CommonAttentionMetadata
 
+from vllm_ascend import envs
 from vllm_ascend.utils import AscendDeviceType, get_ascend_config, get_ascend_device_type
 
 
@@ -302,3 +303,8 @@ def transdata(nd_mat, block_size: tuple = (16, 16)):
     )
     nz_mat = torch.reshape(nz_mat, (nz_mat.shape[0], nz_mat.shape[1] * nz_mat.shape[2], nz_mat.shape[3]))
     return nz_mat
+
+
+def enabling_malpo(vllm_config: VllmConfig) -> bool:
+    is_decode_instance = vllm_config.kv_transfer_config is not None and vllm_config.kv_transfer_config.is_kv_consumer
+    return bool(envs.VLLM_ASCEND_ENABLE_MLAPO and is_decode_instance)