[compile] Stop one-off setting enable_aot_compile and use context manager instead. (#30503)

Signed-off-by: zhxchen17 <zhxchen17@fb.com>

vllm/compilation/wrapper.py

@@ -171,15 +171,17 @@ class TorchCompileWithNoGuardsWrapper:
 
             compiled_ptr = self.check_invariants_and_forward
 
+        aot_context = nullcontext()
         if envs.VLLM_USE_AOT_COMPILE:
             if hasattr(torch._dynamo.config, "enable_aot_compile"):
-                torch._dynamo.config.enable_aot_compile = True
+                aot_context = torch._dynamo.config.patch(enable_aot_compile=True)
             else:
                 msg = "torch._dynamo.config.enable_aot_compile is not "
                 msg += "available. AOT compile is disabled and please "
                 msg += "upgrade PyTorch version to use AOT compile."
                 logger.warning(msg)
 
+        with aot_context:
             self._compiled_callable = torch.compile(
                 compiled_ptr,
                 fullgraph=True,