RESTBase: use the domain name as defined by role::mediawiki
RESTBase: use the domain name as defined by role::mediawiki

Instead of 'hard-coding' RESTBase's domain to 'localhost', use the
hostname as provided by role::mediawiki(::hostname), since this is the
same domain name as used by Parsoid as well.

Bug: T111223
Change-Id: I0b50af3854c7c55d6553563e81ddc5917d9d7757

HarriAlasi/wiki3dviewer,HarriAlasi/wiki3dviewer,HarriAlasi/wiki3dviewer,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,HarriAlasi/wiki3dviewer,stuartbman/mediawiki-vagrant,stuartbman/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,HarriAlasi/wiki3dviewer,wikimedia/mediawiki-vagrant,HarriAlasi/wiki3dviewer,HarriAlasi/wiki3dviewer,stuartbman/mediawiki-vagrant,stuartbman/mediawiki-vagrant,wikimedia/mediawiki-vagrant,stuartbman/mediawiki-vagrant,stuartbman/mediawiki-vagrant