LIBTD-1425: Compel Seamus admin_set_id cleanup

Addition to the seamus cleanup scripts to set all works to be part of the default admin set.

This assumes that the other import scripts have been run already. For example:

bin/rake seamus:import_authors["input.xml"] 
bin/rake seamus:import_items["input.xml"] 
bin/rake seamus:cleanup_users 

Then, you can run the modified task:

bin/rake seamus:cleanup_works