Inject correct sftp-server path in OpenSSH config

Summary:
The sshd_config needs to get the sftp-server path,
a file varying widely from one distro to another.

Test Plan:

• Check paths
• Ensure map.jinja compile
• sftp ysul.nasqueron.org

Reviewers: dereckson

Reviewed By: dereckson

Differential Revision: https://devcentral.nasqueron.org/D1077