Remove "Release Counter" from Releeph

Summary: Fixes T3658. This field doesn't make much sense and doesn't appear to ever have actually been implemented. Particularly, the %N pattern doesn't actually work and I can't find anything which actually calls this stuff or exposes it externally. Facebook doesn't use it (see T3658) and I don't think it's useful in general.

Test Plan: Used grep to look for stuff, edited a project.

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T3658

Differential Revision: https://secure.phabricator.com/D8628