Remove qpress/QuickLZ from MariaDB-Backup

The QuickLZ tool has been abandoned since 2011 with no new releases in 10+ years: http://www.quicklz.com/

Percona Xtrabackup and MariaDB Backup however still uses it as the only built-in compression library.

The --compression option is marked as deprecated at https://mariadb.com/kb/en/mariabackup-options/#-compress (however the program does not yield any errors about deprecation when run). In issues like MDEV-17600 and MDEV-26810 wlad keeps repeating that compression is deprecated.

Frequently referenced tutorials such as https://mariadb.com/kb/en/using-encryption-and-compression-tools-with-mariabackup/ continue to show --compression as a viable option but probably the general attitude is that it should be phased out.

The binary qpress is not included in any modern Linux distro (and was never in e.g. Debian) and causes issues such as MDEV-15069. Usage of this compression is probably already very low.

I propose that it would be removed completely, or alternatively replaced by 7z or some other compression method with easily available open source library.