[Task]: Identify dead code in addons-server

[KevinMind]

Description

We can add a CI check to ensure we remove deadcode from our codebase.

There are tools like https://github.com/jendrikseipp/vulture that can help with this

Acceptance Criteria

Milestones/checkpoints

Beta Give feedback

1. A check that searches the codebase for deadcode and flags high likely dead code paths.
2. Integration to CI to ensure we do not merge dead code

Checks

• If I have identified that the work is specific to a repository, I have removed "repository:addons-server" or "repository:addons-frontend"

┆Issue is synchronized with this Jira Task

[diox]

I'm not sure it's worth the effort depending on how annoying it is to set up, because I'm fairly confident we don't have that much dead code, we've already done a lot of cleanups over the years.

The one thing we may have are obsolete management commands for one-off tasks we then never deleted, but even those we tend to eventually get rid off (some already have issues opened about them)