[sledge] Remove disequality formula
[sledge] Remove disequality formula

Summary: It is redundant with `Not Eq`

Reviewed By: jvillard

Differential Revision: D24306046

fbshipit-source-id: fbfba5c59

jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer,jvillard/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer