[backport][dask] Disable broadcast in the scatter call. (dmlc#10632) (dmlc#10634)

Author: trivialfis

python-package/xgboost/dask/__init__.py

@@ -1237,12 +1237,14 @@ def _infer_predict_output(
 async def _get_model_future(
     client: "distributed.Client", model: Union[Booster, Dict, "distributed.Future"]
 ) -> "distributed.Future":
-    # See https://github.com/dask/dask/issues/11179#issuecomment-2168094529 for
-    # the use of hash.
+    # See https://github.com/dask/dask/issues/11179#issuecomment-2168094529 for the use
+    # of hash.
+    # https://github.com/dask/distributed/pull/8796 Don't use broadcast in the `scatter`
+    # call, otherwise, the predict function might hang.
     if isinstance(model, Booster):
-        booster = await client.scatter(model, broadcast=True, hash=False)
+        booster = await client.scatter(model, hash=False)
     elif isinstance(model, dict):
-        booster = await client.scatter(model["booster"], broadcast=True, hash=False)
+        booster = await client.scatter(model["booster"], hash=False)
     elif isinstance(model, distributed.Future):
         booster = model
         t = booster.type