Sat5 + Sat6: check for database inconsistencies

[jhutar]

Check for data in tables that refers to parent data that doesn't exist:

Satellite 5:
    select * from rhnchannelerrata where channel_id not in (select id from rhnchannel)
    select * from rhnchannelerrata where errata_id not in (select id from rhnerrata) 

There are probably many similar things to look for in Satellite 6