[2/2] Support deterministic inference for temperature > 0 (#10678)

Co-authored-by: Baizhou Zhang <sobereddiezhang@gmail.com>
Co-authored-by: hebiao064 <hebiaobuaa@gmail.com>

sgl-router/tests/test_openai_routing.rs

@@ -68,6 +68,7 @@ fn create_minimal_completion_request() -> CompletionRequest {
         lora_path: None,
         session_params: None,
         return_hidden_states: false,
+        sampling_seed: None,
         other: serde_json::Map::new(),
     }
 }