.circleci: Move docker_build workflow to codegen (#40189)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40189
This is to allow for easier modification later on down the road.
Makes no actual modification to the `.circleci/config.yml`
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Test Plan: Imported from OSS
Differential Revision: D22119414
Pulled By: seemethere
fbshipit-source-id: c6cb105d983e43ae1bf289b2d9f734b34a7febe2
