The display name can be set by the user in the preferences. But for each
host you can also set a default for what should happen, if that display
name is not set. Normally that default would be 'FULL_NAME'. Thus this
change will not yet change anything for any user, but for gerrit-review,
where the default was already changed to FIRST_NAME.
Screenshot of using FIRST_NAME: https://imgur.com/a/pQoJFHk
Change-Id: Ibc3bc74216c8d3d7e7add831aa553a825bd8a1ae
9fcb519992