[dataimport] Drop reference to the 'source' column (closes #4067694).
CW 3.19 drops the multi-source support. This column does not exist in 3.19.
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s precreate script, executed at instance creation time or when
the cube is added to an existing instance, before the schema is serialized.
This is typically to create groups referenced by the cube'schema.
"""