Return 0 at the end of 60-mediawiki-vagrant.

The test for landscape-sysinfo was causing the script to return
a failure code if landscape-sysinfo isn't available.  This caused
some messiness in labs-vagrant.

Change-Id: I202ebd79fdedba7c90c0db98d0d02cad09c85629
Merge "Return 0 at the end of 60-mediawiki-vagrant."