Remove GetUsersAllowedForSupervisedUsersCreation

The method seems to be unused.

Change-Id: I8c3a49c2403c5aadd93f9f3acc256cf3dda7e5ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1565634
Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#651081}
8 files changed