[Bugfix] Strengthen the check of X-data-parallel-rank in Hybrid LB mode (#32314)

Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>

vllm/config/parallel.py

@@ -361,6 +361,14 @@ class ParallelConfig:
     def num_ubatches(self) -> int:
         return 2 if self.enable_dbo else self.ubatch_size
 
+    @property
+    def local_engines_only(self) -> bool:
+        """
+        Client manages local+remote EngineCores in pure internal LB case.
+        Client manages local EngineCores in hybrid and external LB case.
+        """
+        return self.data_parallel_external_lb or self.data_parallel_hybrid_lb
+
     def get_next_dp_init_port(self) -> int:
         """
         We might need to initialize process groups in multiple