Remove cols and rows preferences
In https://gerrit.wikimedia.org/r/80061/, Chad was convinced this
preference is barely used and mostly set to weird values by people
who don't understand what they're doing.
He made some quick stats: http://p.defau.lt/?fgGU0StB4J9l0LC5GZq8AA
Used defaults of 80 columns and 25 rows in places that still
were asking for it. The old default values are left in
$wgDefaultUserOptions for now, since various extensions are
The 'rows' and 'columns' messages don't appear to be in use in
any extensions in Git, so I killed those as well.
(This is the same as I642188c74d929a586b1882a1cf8656056c4fcf5a.)