cbc trials factor discussion

Currently the cbc trials factor is listed as 6 due to prematurely assuming cwb-bbh will be treated as a cbc search at the beginning of O4. We need to fix that and read the surrounding text to make sure all of the numbers are representative of what's actually in the code at the moment and drop references to treating cwb-bbh as a cbc search (like the line about a cbc-focused burst search).