Remove /var/lib/mongodb from mongodb-org[-unstable] deb metapackage

The ongodb-org[-unstable] deb metapackage includes a /var/lib/mongodb directory owned by root. When installing this package, the mongodb-org[-unstable]-server package would

chown mongodb:mongodb /var/lib/mongodb

so MongoDB would run.

However, after the changes in SERVER-23516 the permissions of /var/lib/mongodb are not updated, so the resulting installation will not be usable until those permissions are fixed.

The proposed solution is to remove /var/lib/mongodb from the mongodb-org[-unstable] metapackage.