Deprecate Sherlock tool

What does this MR do and why?

Deprecates Sherlock and removes related code & specs. The rblineprof gem (used by Sherlock; outdated), GDK config, and related documentation will be removed separately.
More details in #349293 (closed).

How to set up and validate locally

Check that the development environment works fine.
Rely on CI.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #349293 (closed)