Log build dependencies cumulative size

What does this MR do and why?

This merge request adds additional instrumentation that will allow us to log the size of all build dependencies' artifacts exposed when a runner picks a job to process.

See gitlab-org/gitlab#362897

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.