Adjust open5gs-latest and osmo-uecups-latest to not hardcode a UID. This is in preparation for creating a "build" user in debian-bookworm-obs-latest, like we have it in debian-bookworm-build.
Copy the block for configuring the build user and disabling man pages from debian-bookworm-build. This fixes failures on ttcn3-ggsn-test-kernel-latest* (non-latest worked fine since these use containers based on debian-bookworm-build).
Fixes: 5a48bfbe ("scripts/kernel-test: build initrd+kernel as user") Change-Id: Idee29d5b9796e8905bdf822d076f25612cbc77a0
