[CrOS Settings] Remove unnecessary comma when no first user is added.

Currently, when no first user is added, there is an unecessary comma on
the popup description when hovering over the owner icon.  This CL
removes that comma and adds the string for when there is no owner.

Change-Id: I2123a1d94e7da551d15f6e178e564ca60ba8980e
Bug: 931612
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1519306
Commit-Queue: Regan Hsu <hsuregan@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640447}
5 files changed