Remove docker_config_defaults from CircleCI config (#53200)
Summary:
It doesn't seem to be used anywhere.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/53200
Test Plan: CI.
Reviewed By: xuzhao9
Differential Revision: D26785924
Pulled By: samestep
fbshipit-source-id: f4698ff2c213d4679e6d76b7677d9b9004917ee1
