Fix Qwen3Next CI Config (#7561)

### What this PR does / why we need it?
This pr modifies qwen3Next nightly CI config. 
(1) Add a nightly CI .
(2) Set a more precise accuracy standard

- vLLM version: v0.18.0
- vLLM main:
6a9cceb219

Signed-off-by: Your Name <you@example.com>
Co-authored-by: Your Name <you@example.com>

tests/e2e/nightly/single_node/models/configs/Qwen3-Next-80B-A3B-Instruct-W8A8.yaml

@@ -41,5 +41,5 @@ test_cases:
         dataset_conf: gsm8k/gsm8k_gen_0_shot_cot_chat_prompt
         max_out_len: 32768
         batch_size: 32
-        baseline: 95
-        threshold: 5
+        baseline: 96
+        threshold: 3