Get rid of Scaleway MOTD

Summary:
Scaleway customizes MOTD in their Debian image.

That conflicts with our MOTD.

Fixes T858.

Test Plan: salt eglide state.apply roles/shellserver/motd

Reviewers: Sandlayth

Maniphest Tasks: T858

Differential Revision: http://devcentral.nasqueron.org/D399