auto-install: disable swap on appservers (mw.cfg)

Disable swap on all (new) appservers. While at it, cleanup preseed.cfg
lines for mw.cfg by removing some stale entries and splitting up the
existing one per role.

There's likely some roles that will need a different profile than the
appserver one, let's do these when the time comes.

Change-Id: Iea1809dcde2e588c2a053598f9c23ec6abf02658