Fix nologin path for Debian

Summary:
On Debian, nologin has been provided by the login package since Debian Sarge, and has always been located at /usr/sbin/nologin.

/sbin/nologin is the Fedora/RHEL/CentOS location.

Test Plan: pwck

Reviewers: dereckson

Reviewed By: dereckson

Subscribers: Nasqueron Docker deployment squad, Sandlayth

Tags: Docker images

Differential Revision: https://devcentral.nasqueron.org/D752