[openSUSE/obs-build] 68cdff: Set home to /root when running build time services

1 Dec 2022

      Branch: refs/heads/master
  Home:   https://github.com/openSUSE/obs-build
  Commit: 68cdff4dd9add887a1af842fba9ea1c2572a2060
      https://github.com/openSUSE/obs-build/commit/68cdff4dd9add887a1af842fba9ea1c...
  Author: Michael Schroeder 
  Date:   2022-12-01 (Thu, 01 Dec 2022)

  Changed paths:
    M build

  Log Message:
  -----------
  Set home to /root when running build time services

This change follows what we did for the post build checks
in commit ae0536347690552b78f946e7d522b0d3251eb4e4.

Fixes #901