Revert "Split `make docker` for GitLab Runner Helper into 'master'"

What does this MR do?

This reverts !1174 (merged) and his fix !1179 (merged)

Why was this MR needed?

!1174 (merged) broke a feature of the runner, it cannot load the precompiled helper image from disk.

Given this was a preparatory work for #3755 (closed) it will be fixed during %11.9 development cycle.

Are there points in the code the reviewer needs to double check?

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Added tests for this feature/bug
• In case of conflicts with master - branch was rebased

What are the relevant issue numbers?