[llvm] [CI] include utils in monolithic scripts (PR #158090)

[Maksim Levental via llvm-commits]

makslevental wrote:

> How are these orthogonal? The only reason to land this PR is for #157944.

Because the other PR isn't finished and I'm going to refactor it to use a CMake configure arg instead of an env variable _but I will still need this change_. 

https://github.com/llvm/llvm-project/pull/158090