Remove 'disable user' logic from _delete_domain_contents

Bug 1130236 has been marked as completed and fix released. This
commit removes the logic in `_delete_domain_contents` that disabled
the users prior to cleaning up the contents of the domain due to the
bug.

Change-Id: I0b1fba429cf45baae88a629e1629ce704dad4246
Merge "Remove 'disable user' logic from _delete_domain_contents"