.github: Run docker containers in detach mode (#64459)

.github: Run docker containers in detach mode (#64459)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64459

Should allow users to exec into the docker container if using with-ssh,
even if the build / test command has finished executing

Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Test Plan: Imported from OSS

Reviewed By: malfet

Differential Revision: D30742797

Pulled By: seemethere

fbshipit-source-id: 969ed8799216c6051439c7d41ab709b2d40938ac