project-lakitu: sys-apps/shadow: relax the constraints on usernames

This commit re-applies commit ea27e37b7fc6
("lakitu: sys-apps/shadow: Relax the constraints on usernames")

BUG=b/170409220
BUG=b/65754927
TEST=See the last commit in this series. Also see the TEST section of
     commit ea27e37b7fc6.
RELEASE_NOTE=Updated shadow tool suite (sys-apps/shadow) to 4.8.1.

Change-Id: I1527edd630a709b459176937c596b82e4b66f13f
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/8323
Reviewed-by: Saied Kazemi <saied@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
4 files changed