R1:03d323e9fdc2

Fix config-migration text for dashboard options

Summary:
The commit which added checks for the old homepage options (now in
Dashboard) in rP9d9a47e9cf, added them to the auth section, where they
would present:
This option has been migrated to the "Auth" application. Your old
configuration is still in effect, but now stored in "Auth" instead of
configuration. Going forward, you can manage authentication from the
web UI.

Remove them from the moved-to-Auth list, and coalesce the multiple
definitions…