utf8 causes display in cli client to be too wide

get_field_disp_length() in mysql.cc (client) uses byte length instead of character length.

The description here makes this clear: https://github.com/MariaDB/server/blob/10.4/client/mysql.cc#L3688

mariadb monitor should use character length (and/or work with server to receive character length and use that in this function)