Avoid passing artifacts `expire_in` to Runner

Summary

We seem to pass artifacts' expire_in param to the Runner when it requests a new job but I have the feeling the Runner does not do anything with it.

The Runner finally returns it to the server when uploading artifacts and at that point it's used to calculate the expire_at date.

Improvements

We don't need to pass expire_in around if it's not used by the Runner. When an artifact is uploaded we can fetch it from the job.options and apply the correct expiration date without relying on the Runner to send it back.

Also, we can reduce the footprint of what the Runner depends on.

Risks

Asses whether the Runner does anything with expire_in parameter

Involved components

lib/api/runner.rb and JobRequest::Artifacts entity.

Optional: Intended side effects

Reduce the data the Runner depends on.