Clean up logspew in monitor cleanup-on-exit
Clean up logspew in monitor cleanup-on-exit

Summary: The monitor's cleanup-on-exit code would spew if the Flow server dies before the monitor tries to kill it.

Reviewed By: jbrown215

Differential Revision: D15562971

fbshipit-source-id: 2f4cba4abc4f3e7de3ddbe4709c6bc29acce4879

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow