Add missing docker build to slow gradcheck label-triggered build (#61941)
Summary:
Currently, when adding the label, it fails like: https://app.circleci.com/pipelines/github/pytorch/pytorch/352569/workflows/d213cbad-edd6-4fe0-a79c-d46f8c0aae85/jobs/14856158
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61941
Reviewed By: suo
Differential Revision: D29827084
Pulled By: albanD
fbshipit-source-id: 134828d36e51324e6b6539dd4bc5f1eebfb89a03
