https://jira.mongodb.org/browse/RUBY-1825 attempted to change our existing collection listing helpers to list all collections, but this broke Mongoid test suite which has the following code:

    Mongoid.default_client.collections.each do |coll|
      coll.delete_many
    end

Subsequently, the above fails thusly:

Mongo::Error::OperationFailure: cannot delete from system namespace (12050)

The existing methods must continue filtering system collections out, and we may consider adding new methods to return system collections.

Note that the driver has 3 listing methods (collection objects, info hashes and names only).