Fix cannot import `paddle.distributed` in python 3.6 on release/2.4 (#47141)

* fix: fix incorrect import

* fix: fix incorrect usage

python/paddle/distributed/communication/stream/recv.py

@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import paddle.distributed.collective as collective
 import paddle.fluid.framework as framework
+from paddle.distributed import collective
 
 
 def _recv_in_dygraph(tensor, src, group, sync_op, use_calc_stream):

python/paddle/distributed/communication/stream/reduce_scatter.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 
 import paddle
-import paddle.distributed as dist
 import paddle.fluid.framework as framework
 from paddle.distributed.communication.group import _get_global_group
 from paddle.distributed.communication.reduce import _get_reduce_op, ReduceOp

python/paddle/distributed/communication/stream/scatter.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 
 import paddle
-import paddle.distributed as dist
 import paddle.fluid.framework as framework
 from paddle.distributed import collective
 
@@ -44,7 +43,7 @@ def _scatter_tensor_in_dygraph(out_tensor, in_tensor, src, group, sync_op,
         raise RuntimeError("Src rank out of group.")
 
     nranks = group.nranks
-    rank = dist.get_rank()
+    rank = paddle.distributed.get_rank()
     if rank == src_rank:
         _check_tensor_shape(out_tensor, in_tensor.shape, nranks)
 
@@ -69,7 +68,7 @@ def _scatter_in_dygraph(tensor, tensor_list, src, group, sync_op,
         raise RuntimeError("Src rank out of group.")
 
     nranks = group.nranks
-    rank = dist.get_rank()
+    rank = paddle.distributed.get_rank()
     if rank == src_rank:
         if len(tensor_list) == 0:
             raise RuntimeError(

python/paddle/distributed/communication/stream/send.py

@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import paddle.distributed.collective as collective
 import paddle.fluid.framework as framework
+from paddle.distributed import collective
 
 
 def _send_in_dygraph(tensor, dst, group, sync_op, use_calc_stream):