Merge #6371: ci: do not build derivations in parallel on GH

8abe646156 fix(ci): do not build derivations in parallel on GH (UdjinM6)

Pull request description:

  ## Issue being fixed or feature implemented
  Should fix GH Guix builds

  develop: https://github.com/UdjinM6/dash/actions/runs/11563155278
  develop + this patch merged into it: https://github.com/UdjinM6/dash/actions/runs/11562899245

  more info https://github.com/dashpay/dash/blob/develop/contrib/guix/README.md#controlling-the-number-of-threads-used-by-guix-build-commands

  ## What was done?

  ## How Has This Been Tested?

  ## Breaking Changes

  ## Checklist:
  - [ ] I have performed a self-review of my own code
  - [ ] I have commented my code, particularly in hard-to-understand areas
  - [ ] I have added or updated relevant unit/integration/functional/e2e tests
  - [ ] I have made corresponding changes to the documentation
  - [ ] I have assigned this pull request to a milestone _(for repository code-owners and collaborators only)_

ACKs for top commit:
  PastaPastaPasta:
    utACK 8abe646156

Tree-SHA512: eb689e69b741958bb65a368af8ab73662724ff8c003a1b162039fbe1b5b322c268de637efc298b17564dafdb76e21bf3f2d10623698bccea1da4684c4b0d2392

.github/workflows/guix-build.yml

@@ -110,7 +110,6 @@ jobs:
         run: |
           docker run --privileged -d --rm -t \
             --name guix-daemon \
-            -e ADDITIONAL_GUIX_COMMON_FLAGS="--max-jobs=$(nproc --all)" \
             -v ${{ github.workspace }}/dash:/src/dash \
             -v ${{ github.workspace }}/.cache:/home/ubuntu/.cache \
             -w /src/dash \