[legacy] clean up legacy code (#4743)

* [legacy] remove outdated codes of pipeline (#4692)

* [legacy] remove cli of benchmark and update optim (#4690)

* [legacy] remove cli of benchmark and update optim

* [doc] fix cli doc test

* [legacy] fix engine clip grad norm

* [legacy] remove outdated colo tensor (#4694)

* [legacy] remove outdated colo tensor

* [test] fix test import

* [legacy] move outdated zero to legacy (#4696)

* [legacy] clean up utils (#4700)

* [legacy] clean up utils

* [example] update examples

* [legacy] clean up amp

* [legacy] fix amp module

* [legacy] clean up gpc (#4742)

* [legacy] clean up context

* [legacy] clean core, constants and global vars

* [legacy] refactor initialize

* [example] fix examples ci

* [example] fix examples ci

* [legacy] fix tests

* [example] fix gpt example

* [example] fix examples ci

* [devops] fix ci installation

* [example] fix examples ci

colossalai/legacy/nn/parallel/data_parallel.py

@@ -5,7 +5,7 @@ from typing import Iterable, Optional, Set
 import torch
 import torch.distributed as dist
 
-from colossalai.tensor import ProcessGroup as ColoProcessGroup
+from colossalai.legacy.tensor import ProcessGroup as ColoProcessGroup
 from colossalai.utils import is_ddp_ignored
 
 from .reducer import Reducer
@@ -34,8 +34,8 @@ class ColoDDP(torch.nn.Module):
     """Distributed data parallel for ColoTensor. Nested ColoDDP is not supported now.
 
     Example:
-        >>> from colossalai.core import global_context as gpc
-        >>> from colossalai.context import ParallelMode
+        >>> from colossalai.legacy.core import global_context as gpc
+        >>> from colossalai.legacy.context import ParallelMode
         >>> model = torch.nn.Linear(20, 1)
         >>> pg = ProcessGroup(tp_degree = world_size//2)
         >>> model = ColoDDP(model, pg)