[Piecewise CUDA Graph] Fix recompile issue for Mixtral and Grok2 (#13667)

Co-authored-by: Minglei Zhu <mingleizhu1122@gmail.com>
Co-authored-by: Ke Bao <ISPObaoke@163.com>
Co-authored-by: Oasis-Git <ayw.sirius19@gmail.com>

python/sglang/srt/models/mixtral.py

@@ -353,6 +353,7 @@ class MixtralForCausalLM(nn.Module):
         )
         self.logits_processor = LogitsProcessor(config)
 
+    @torch.no_grad()
     def forward(
         self,
         input_ids: torch.Tensor,