Fix transformer unittest

* parallel run dist ci

* test=develop

* update test=develop

- add naive executor
- fix concurrency performance issue

Add warning when disable test_fuse_elewise_add_act_pass on Mac

enforce test_parallel_executor_transformer and test_image_classification_resnet to run in serial (#12545)

* get diff for all changes in current branch

* diff with upstream/develop

* let dist test serial

* 1. Remove PYTHON_FLAGS from paddle_build.sh in paddlepaddle/paddle:latest-dev

* 1. Add PYTHON_FLAGS back
2. Change SIGKILL to SIGINT and SIGTERM

* 1. Add setup.py.in back

* 1. add pip install open-cv in Dockerfile to avoid libusb_exit hanging up which is caused by the opencv-python package missing

* 1. Add the && \ to line above

* 1. Remove the notice comment