[Doc] Upgrade env VLLM_ASCEND_ENABLE_FUSED_MC2 used in nightly test and tutorials (#8441)

### What this PR does / why we need it?
The env `VLLM_ASCEND_ENABLE_FUSED_MC2` should only enabled in the
decoder node during Prefill-Decode Disaggregation scenario

---------

Signed-off-by: wangli <wangli858794774@gmail.com>

tests/e2e/nightly/multi_node/config/Qwen3-235B-disagg-pd.yaml

@@ -10,7 +10,6 @@ env_common:
   OMP_PROC_BIND: false
   OMP_NUM_THREADS: 1
   VLLM_ASCEND_ENABLE_FLASHCOMM1: 1
-  VLLM_ASCEND_ENABLE_FUSED_MC2: 2
   TASK_QUEUE_ENABLE: 1
   SERVER_PORT: 8080
   
@@ -21,6 +20,9 @@ disaggregated_prefill:
 
 deployment:
   -
+    envs:
+      # should disable this in the prefiller node
+      VLLM_ASCEND_ENABLE_FUSED_MC2: 0
     server_cmd: >
         vllm serve "Qwen/Qwen3-235B-A22B"
         --host 0.0.0.0
@@ -57,6 +59,8 @@ deployment:
         }'
 
   -
+    envs:
+      VLLM_ASCEND_ENABLE_FUSED_MC2: 2
     server_cmd: >
         vllm serve "Qwen/Qwen3-235B-A22B"
         --host 0.0.0.0

tests/e2e/nightly/single_node/models/configs/GLM-4.7.yaml

@@ -12,7 +12,6 @@ _envs: &envs
   VLLM_ASCEND_BALANCE_SCHEDULING: "1"
   VLLM_ASCEND_ENABLE_TOPK_OPTIMIZE: "1"
   VLLM_ASCEND_ENABLE_FLASHCOMM1: "1"
-  VLLM_ASCEND_ENABLE_FUSED_MC2: "1"
 
 _server_cmd: &server_cmd
   - "--enable-expert-parallel"

tests/e2e/nightly/single_node/models/configs/Qwen3-VL-235B-A22B-Instruct-W8A8.yaml

@@ -10,7 +10,6 @@ _envs: &envs
   HCCL_BUFFSIZE: "1536"
   PYTORCH_NPU_ALLOC_CONF: "expandable_segments:True"
   VLLM_ASCEND_ENABLE_FLASHCOMM1: "1"
-  VLLM_ASCEND_ENABLE_FUSED_MC2: "1"
   VLLM_ASCEND_ENABLE_NZ: "2"
   VLLM_ASCEND_BALANCE_SCHEDULING: "1"
   SERVER_PORT: "DEFAULT_PORT"

tests/e2e/nightly/single_node/models/configs/Qwen3.5-397B-A17B-W8A8-mtp-A3.yaml

@@ -13,7 +13,6 @@ test_cases:
       OMP_NUM_THREADS: "1"
       TASK_QUEUE_ENABLE: "1"
       SERVER_PORT: "DEFAULT_PORT"
-      VLLM_ASCEND_ENABLE_FUSED_MC2: "1"
       VLLM_ASCEND_ENABLE_FLASHCOMM1: "1"
     server_cmd:
       - "--tensor-parallel-size"