Remove cols and rows preferences

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
using them.

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.)

Bug: T26430
Change-Id: I6c9802bc4f9cf32fb75c3dd7b9e2dc18f271eedf