A --ps cleanup for MDEV-12658 Make the third parameter to LPAD and RPAD optional
A --ps cleanup for MDEV-12658 Make the third parameter to LPAD and RPAD optional

"mtr --ps func_str" failed:
pad_str was erroneously appended with a new space on every PS execution.

Adding pad_str.length(0) into fix_length_and_dec() to avoid this.

natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2,natsys/mariadb_10.2