[ENG-4747](https://linear.app/comm/issue/ENG-4747)
Depends on D9290
After D9290 and D9291 all cookies are from the request body so we can stop tracking this information. This diff removes `cookieSources` and simplifies all conditionals where it mattered.
Note: Like D9291, landing this diff will need to be defered for a while to allow older clients to migrate