Log the value of `Cf-Worker` header from Cloudflare

What does this MR do and why?

Based on the discussion in #474268 (comment 2050642567), we need to log the value of the cloudflare header Cf-Worker.

Cloudflare documentation: https://developers.cloudflare.com/fundamentals/reference/http-request-headers/#cf-worker

This MR follows the same patten used to introduce logging of Cf-IpCountry recently: !146833 (merged)

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Related to #474268 (closed)