remove some stray bits of the reaper_thread
remove some stray bits of the reaper_thread

Summary: I thought I got it all when I moved the triggers over to PubSub, but I missed these bits.

Reviewed By: farnz

Differential Revision: D4140061

fbshipit-source-id: ba6150472d274d3ba309c4aad5cdbc752b9c67d3

wez/watchman,facebook/watchman,wez/watchman,nodakai/watchman,nodakai/watchman,wez/watchman,facebook/watchman,kwlzn/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,kwlzn/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,wez/watchman,kwlzn/watchman,wez/watchman,wez/watchman,kwlzn/watchman,kwlzn/watchman,kwlzn/watchman,wez/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,wez/watchman,nodakai/watchman,kwlzn/watchman