* [CodeStyle][py2] remove `six` package (part2)

* six.ensure_str

* remove unused `import six`

* remove six from BUILTIN_LIKELY_MODULES

* remove six in example code

* remove some decode

* try to fix example code

* fix MockEtcdClient get/get_prefix returns data type

* fix MockEtcdClient get_prefix returns data

* fix MockEtcdClient get returns data

* remove `six` in pypi and conda requirements

* fix MockEtcdClient add_watch_callback/add_watch_prefix_callback returns data type

* refine MockEtcdClient

* update config

* re-blacken python code

* temporarily disable date and diff_py_file

* skip a format

* [CodeStyle][F401] remove unused import in python/paddle/distributed

* remove pass

* empty commit

* Fix ValueError: list.remove(x): x not in list for meta_optimizer_names.

Fix ValueError: list.remove(x): x not in list for meta_optimizer_names.

* Fix split import.

Fix split import.

* add noqa after meta_optimizers in factory

* restort collective ops

* expand `import *`

* add noqa after required imports

* try to fix APIs without core.ops

* Revert "try to fix APIs without core.ops"

This reverts commit 6172beaf601e84bf61f2490c12c4739f0edaa5eb.

* fix an increment

* empty commit

* add noqa after required imports

* expand `import *`, fix ci error
Co-authored-by: NShuangchi He <34329208+Yulv-git@users.noreply.github.com>

* Update README.md

* Update README.md

* Fix F541 by converting f-string to normal strings

uniform logger manager in FleetAPI.
hidde API under distributed/utils which users don't need.

* trim trailing whitespace

* fix `.cmake-format.py`

* revert npu ut changes, avoid npu ci error

* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

* [Auto Parallel] elastic support auto parallel re-launch

* [Auto Parallel] elastic support auto parallel re-launch

* fix ci issue

* fix ci issue

* fix rank mapping unittest

* fix rank mapping unittest

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fix ci issue

* fleet support elastic train

* fleet support elastic train

* support elastic

* add unittest

* fix unitest bug

* fix unittest bug

* fix unittest bug

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix elastic bug

* fix ci fail

* fix ci fail

* fix elastic bug

* fix elastic bug

* fix joint debugging bug

* fix joint debugging bug

* fix windows ci failed

* fix windows ci failed

* Optimize fleet elastic scale in/out

* elastic support pre hook

* add prehook unittest

* fleet support elastic train

* fleet support elastic train

* support elastic

* add unittest

* fix unitest bug

* fix unittest bug

* fix unittest bug

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix unittest coverage

* fix elastic bug

* fix ci fail

* fix ci fail

* fix elastic bug

* fix elastic bug

* fix joint debugging bug

* fix joint debugging bug

* fix windows ci failed

* fix windows ci failed

* fix force kill for elastic

* kill process by group

* add random and prevent deadlock

* elastic unitest

* rename demo

* elastic etcd ready