clean up Rechecker.recheck_single
clean up Rechecker.recheck_single

Summary:
~files_to_force is unused after removing global find-refs

Changelog: [internal]

Reviewed By: samwgoldman

Differential Revision: D31867197

fbshipit-source-id: d0d00d9c28d283e3aae66b9f80fd7719725c3219

mroch/flow,facebook/flow,facebook/flow,facebook/flow,mroch/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow,facebook/flow,mroch/flow