Resolve precendence issues on build_runner_presenter

What does this MR do and why?

This MR aims to resolve gitlab-runner#28894 (comment 2712259909)

The problem was that build.variables was used without using to_hash on the variables collection which is responsible for applying the variable precedence logic.

This also indicates a larger-scoped problem where the variables collection and builder are too open ended and lead to scope creep as seen in this instance.

How to set up and validate locally

Follow the steps on the original bug report: gitlab-runner#28894 (closed)

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