Fix [#33997] Units Scale in Metric mode displays wrong face area.

Also now display nice "area" units (maybe using "length" units was a perf matter, but anyway, you can't have more than a few tens of values displayed at a time, after that they become unreadable). Easy to undo anyway if we really want to keep ugly "10m" as area display!

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54101 954f8c5b-7b00-dc11-b283-0030488c597c