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>

tests/e2e/nightly/single_node/models/test_deepseek_r1_0528_w8a8.py

@@ -31,7 +31,6 @@ MODELS = [
 MODES = [
     "single",
     "aclgraph",
-    "aclgraph_mlapo",
 ]
 
 prompts = [
@@ -88,8 +87,6 @@ async def test_models(model: str, mode: str) -> None:
     ]
     if mode == "single":
         server_args.append("--enforce-eager")
-    if mode == "aclgraph_mlapo":
-        env_dict["VLLM_ASCEND_ENABLE_MLAPO"] = "1"
     server_args.extend(["--additional-config", json.dumps(additional_config)])
     request_keyword_args: dict[str, Any] = {
         **api_keyword_args,

tests/e2e/nightly/single_node/models/test_deepseek_r1_0528_w8a8_eplb.py

@@ -56,7 +56,6 @@ async def test_models(model: str) -> None:
         "OMP_NUM_THREADS": "100",
         "OMP_PROC_BIND": "false",
         "HCCL_BUFFSIZE": "200",
-        "VLLM_ASCEND_ENABLE_MLAPO": "1",
         "VLLM_RPC_TIMEOUT": "3600000",
         "VLLM_EXECUTE_MODEL_TIMEOUT_SECONDS": "3600000",
         "DISABLE_L2_CACHE": "1",